{ "items": [ { "title": "Spitzer Space Telescopes", "url": "http://blog.sedscelestia.org/Spitzer-Space-Telescope/", "date": "September 20, 2022", "category": "Telescopes", "tags": ["Science","Telescope-Series","Astronomy"], "author": "Dhruv Parashar", "content": "The Spitzer Space Telescope was launched 25th August 2003. It was an infrared telescope. It was just the third telescope dedicated to infrared astronomy. Its groundbreaking technology has inspired numerous other space exploration missions. That is why even after the operations of the telescope ended in November 2020, this telescope holds a special position in the realm of telescopes. Another lesser known fact of the SST is that it is the last of the 4 coveted NASA’s great laboratories. It was earlier named the Space Infrared Telescope Facility (SIRTF). It got its name from a contest that was open to the public, much unlike the traditional naming practices of telescopes, which is done by a board of scientists.NASA’s Spitzer Space TelescopeCredits: Space.comOBJECTIVES:The Spitzer Space Telescope studied the early universe, young galaxies and formation of stars. It was also used to detect dust disks around stars which is considered an important signpost of planetary formation. All of this was done with the help of the Infrared technology on which it was based on.Spitzer was capable of capturing both images and spectra by detecting infrared (IR) wavelengths. The telescope detects infrared (IR) energy between wavelengths of 3 and 180 microns. Among the other great laboratories, each telescope observes different wavelengths: Hubble observes visible radiation, Chandra observes x-ray radiation and Compton observes gamma ray radiation. The Spitzer telescope offers us a completely unique photo that our eyes can’t see. For example, It can locate IR mild via vast, dense clouds of gas and dirt which block visible mild. Inside of those dense clouds of gas there may be new stars forming or newly forming planetary systems. Spitzer can examine truly dim, smaller stars or at large molecular clouds.A labeled space image comparing views of a supernova remnant by three different Great observatories.Credits: WikipediaINSTRUMENTS:Infrared Array Camera (IRAC)Infrared camera operating simultaneously at four wavelengths (3.6 μm, 4.5 μm, 5.8 μm, 8 μm). For each module he used a 256 by 256 pixel detector—the short wavelength pair used indium antimonide technology and the long wavelength pair used arsenic-doped silicon bandline technology. It was Giovanni Fazio of the Physics Center. Harvard & Smithsonian; flight hardware was built by NASA Goddard Space Flight Center.Infrared spectrometer (IRS)Infrared spectroscopy with four sub-modules operating at wavelengths 5.3-14 μm (low resolution), 10-19.5 μm (high resolution), 14-40 μm (low resolution), and 19-37 μm (high resolution) Total. Each module used a detector of 128 × 128 pixels - the short wavelength pair used arsenic-doped silicon block impurity band technology and the long wavelength pair used antimony doped silicon block impurity band technology. The principal investigator was James R. Houck of Cornell University; the flight hardware was built by Ball Aerospace.Multiband Imaging Photometer (MIPS) for SpitzerThree mid-far infrared detector arrays (128 × 128 pixels at 24 µm, 32 × 32 pixels at 70 µm, 2 × 20 pixels at 160 µm). The 24 μm detector is identical to one of the IRS shortwave modules. The 70 μm detector used gallium-doped germanium technology, and the 160 μm detector also used gallium-doped germanium, but stress was applied to each pixel to reduce the bandgap and reduce sensitivity to this long wavelength. has expanded. The principal investigator was George H. Riecke of the University of Arizona. The hardware was manufactured by Ball Aerospace.The instruments are cooled with liquid helium (this is called cryogenically cooled). This peculiar element is seen in this telescope because it needs to be cooled as it is prone to get heat interference as it is actually observing heat ! The telescope also carries a special solar shield to protect from the heat from the Sun.The Helix Nebula, blue shows infrared light of 3.6 to 4.5 micrometers, green shows infrared light of 5.8 to 8 micrometers, and red shows infrared light of 24 micrometersCredits: WikipediaDISCOVERIES:The major discoveries include: The first exoplanet weather map. The largest known ring around Saturn. Buckyballs in space. Exoplanet atmospheres. Faraway black holes. ‘Big baby’ galaxies.Warm Mission & Decommissioned:In 2009, Spitzer ran out of liquid coolant and began its “warm mission,” refocusing its studies on determining how quickly our universe is stretching apart, and characterizing asteroids and the atmospheres of gas-giant planets. Spitzer operated in its warm mission for over a decade, or about twice the length of its primary mission. On Jan. 30, 2020, engineers decommissioned the spacecraft, bringing the Spitzer mission to a close.A labeled space image comparing views of a supernova remnant by three different Great observatories.Credits: WikipediaThe “Beyond” Mission:The most fascinating part of the mission is that even after accomplishing all of the objectives, the Spitzer even laid groundwork for the James Webb Space Telescope(JWST). It identified candidates for a detailed research mission of the JWST.This leg of the mission started on 1st October 2016 and went on till 2.5 years.Conclusion:Spitzer’s accomplishments were simply amazing in its 16 years of active service. Spitzer discovered a giant ring of Saturn, revealed a system of seven Earth-size planets around a star which is 40 light-years away, and studied the most distant known galaxies & so much more. Spitzer indeed was an engineering marvel which not only accomplished its objectives but even laid the foundation for its successor, the James Webb Space Telescope. The research done by Spitzer has been inspiring and this legend will definitely be credited for many more future projects to come.References: Spitzer Space Telescope - Wikipedia Spitzer - Universe Missions - NASA Jet Propulsion Laboratory Spitzer Space Telescope - Britannica 15 of Spitzer’s Greatest Discoveries From 15 Years in Space - NASA JPL The Spitzer Space Telescope’s greatest exoplanet discoveries - Space How does the Spitzer Telescope work? Great Observatories program - Wikipedia" } , { "title": "MOST Space Telescopes", "url": "http://blog.sedscelestia.org/MOST-Space-Telescope/", "date": "September 6, 2022", "category": "Telescopes", "tags": ["Science","Telescope-Series","Astronomy"], "author": "Varun Iyer", "content": "The MOST (Microvariability and Oscillations of Stars) Telescope, also referred to as the “Humble Space Telescope” was not only Canada’s first space telescope launched in 2003 but also the first Canadian science satellite launched since ISIS II. It was the first spacecraft dedicated to the study of asteroseismology, subsequently followed by the now-completed CoRoT and Kepler missions. It was the smallest space telescope in orbit until 2013.DescriptionThe projected was initiated in 1996 by a group of researchers: Slavek Rucinski of Ontario’s Centre for Research in Earth and Space Technology, Jaymie Matthews of the University of British Colombia, Tony Moffat of the University of Montreal, and Kieran Carroll of Dynacon Enterprises. In 1997, the Canadian Space Agency agreed to finance the project and Jaymie Matthews was named Principal Investigator and Mission Scientist.Canadian Space Agency’s Space Science Branch, and was funded under its Small Payloads Program; its operations were (as of 2012) managed by the CSA’s Space Exploration Branch. It was operated by SFL (where the primary MOST ground station is located) jointly with Microsat Systems Canada Inc. (since the sale of Dynacon’s space division to MSCI in 2008).As of ten years after launch, despite failures of two of its components (one of the four reaction wheels and one of the two CCD driver boards), the satellite was still operating well, as a result of both on-going on-board software upgrades as well as built-in hardware redundancy, allowing improvements to performance and to reconfigure around failed hardware units.Unique Selling PointThe MOST satellite is unique not only because of its small size, but because it can conduct stellar measurements from space. Traditionally, scientists have relied upon expensive, Earth-based telescopes to provide research data. These instruments have been hampered by both the Earth’s distorting atmosphere and its rotation—allowing for only a partial viewing of a star due to the day-night cycle. In space, the MOST telescope has a direct and constant view of a star for up to seven weeks at a time and can downlink data to ground stations at the University of British Columbia and the University of Toronto. The telescope is mounted on a platform about the size of a suitcase. The ability to use such a small satellite for a space telescope is made possible by Dynacon’s light gyroscope technology that corrects the wobbling motion of the satellite and accurately controls where the satellite is pointing. MOST can see changes in the brightness of the star, or the planet associated with it, down to levels of one part in a million: that’s one ten thousandth of a percent. Despite its diminutive size, it is ten times more sensitive than the Hubble Space Telescope in detecting the minuscule variations in a star’s luminosity caused by vibrations that shake its surface.MOST would be the first instrument in history capable of detecting rapid brightness oscillations in Sun-like stars, to seismically probe their interiors and giving direct information about the atmospheres of these mysterious worlds. At the same time, data on the oscillations of the parent stars would specify the ages of these stellar/planetary systems – an important test of models of how these planets formed and evolved.MissionThe satellite’s mission is to conduct long-duration stellar photometry observations in space. The primary science objectives include: measuring light intensity oscillations in solar type stars; determining the age of nearby “metal-poor sub-dwarf” stars, which in turn allows a lower limit to be set on the age of the Universe; and detecting the first reflected light from orbiting exoplanets and using it to determine the composition of their atmospheres. It also performs ultra-high-precision photometry (i.e., measurement of brightness variations to a level of 1 part per million) of stars down to the naked-eye limit of visibility (magnitude 6) for up to two months without major interruptions. (Note: To put the sensitivity of MOST in perspective, look at a streetlamp 1 km away and then move your eye 0.5 mm closer to it. The streetlamp is now about 1 ppm brighter to your eye.)MOST was initially designed to study vibrations of stars for stellar seismology, but a while after its launch it was pointed at stars having mysterious exo-planets (extra-solar planets) around them, which gave the team clues about the atmospheres of these planets. The way it does this is to look for subtle variations in the light coming from these star systems, either from the star itself or from the planet that is orbiting around it. The telescope will complete one orbit around the Earth every 101 minutes by passing over each of Earth’s poles. It will spend 60 days on each star studied. MOST original mission was supposed to last one year and to allow the study about 10 stars, but was operational even after more than 16 years in space (end of mission March 2019) and was involved in the observation of more than 5,000 stars.Originally designed to detect rapid brightness oscillations in Sun-like stars, to seismically probe their interiors, however, once the project had passed the critical design phase, it was realised the MOST instrument was more sensitive and versatile than originally expected in Phase A. It also had the potential to detect reflected light from some of the giant planets recently discovered to be orbiting other nearby stars. The amount of light reflected and scattered back to Earth by such an exoplanet would vary during the planet’s orbit, as it goes through illumination phases like those of the Moon or of Venus, as first observed telescopically by Galileo in the early 1600’s. Therefore, in Phase C of the project, the MOST team added an exciting new science application, without changing the hardware or software design, or the selected orbit, and at no added cost.Design and InstrumentsThe design of MOST was inspired by and based on microsatellite bus designs pioneered by AMSAT, and first brought to commercial viability by the microsatellite company SSTL (based at the University of Surrey in the UK); This approach to satellite design is notable for making use of commercial-grade electronics, along with a “small team,” “early prototyping” engineering development approach rather different from that used in most other space-engineering programs, to achieve relatively very low costs: MOST’s life-cycle cost (design, build, launch and operate) was less than $10 million in Canadian funds (about 7 million Euros or 6 million USD, at exchange rates at time of launch)Weighing about 53 kg (117 lb), being 60 cm (24 in) in width and height, and 24 cm (9 in) in depth, it is comparable to the size and weight of a small chest of an extra-large suitcase filled with electronics.MOST TelescopeCredits: Astro CanadaInstruments: Optics: 15-cm aperture f/5.88 Maksutov telescope with a 0.86 deg unvignetted FOV Two (2) 1024x1024 frame-transfer CCDs, focal plane passively cooled to < -40CMicrosatellite Bus Features: Orbit: 750-900 km altitude, circular, dawn/dusk sun-synch (i=98 deg, 6 PM ascending node) Attitude Control: less than 1 arcsec pointing error using a star tracker, Sun sensors, magnetometers, reaction wheels and magnetic torque rods Power: 30-35W orbit-average power, using silicon solar arrays on all 6 sides, NiCd batteries On-Board Computers: 1 NEC/V53 housekeeping processor, four 80-MIPS DSPs for attitude control, CCD read-out and science data processing, 48 Mbytes RAM-disc Telemetry & Telecommand: S-band packet-protocol uplink and downlink, 9.6 kbps up, 38.4 kbps down, 100-120 minutes/day contact time via 2 ground stations.An optical Telescope with a collecting mirror only 15 cm across, feeding a CCD (Charge Coupled Device) camera with twin Marconi 47-20 frame-transfer devices (1024 by 1024 pixels) side-by-side. One CCD is used for science measurements; the other is read out every second to track guide stars for satellite attitude control. The Instrument contains a single broadband filter which selects light in the wavelength range 350 - 700 nm.The camera is equipped with an array of Fabry microlenses which project a large stable image of the Telescope pupil illuminated by target starlight, which is key to the photometric precision of MOST. For low cost and high reliability, the Instrument has no moving parts - the structure automatically maintains the same focus across a wide range of temperatures, and exposure times are controlled by rapid frame transfer of the CCDs. The CCDs are cooled by a passive radiator system.This Instrument is powered by solar panels and oriented by a system of miniature reaction wheels and magneto- torquers. The attitude control system should keep the Telescope pointing within 10 arcseconds of the desired target 99% of the time. This is an improvement of two orders of magnitude over previous micro-satellite pointing capability.DiscoveriesThe first major discovery made by the telescope occurred as soon as it became operational. The discovery was that Procyon, one of the most studied stars, shows no pulsations at all, which contradicts 20 years of ideas and observations, and forced astronomers to rethink their models for stars. (Note- Procyon is a star in our Galaxy that is two times larger and seven times brighter than the Sun. However, the star has entered the last phase of its life and is becoming dimmer. As a result of studies conducted on the oscillation of the Sun, scientists have long believed that Procyon and other stars like it in the Milky Way emit similar pulses. MOST has proved them wrong. Procyon is the eighth in importance in the night sky for its brightness. It is located in the Small Dog constellation (Canis Minor))Small Dog constellation (Canis Minor)Credits: Go AstronomyIn 2005, MOST was responsible for another surprising discovery: it observed a giant planet that orbits so close to its host star that the star was forced to synchronize its rotation with that of the planet. Normally, it is the other way around: a planet synchronizes its orbit with that of its host star.In 2006, continuous observation of the HD 163899 star over a period of 37 days confirmed that it is a totally new variable star class, namely slowly pulsating B supergiants. (SPBsg)In 2011, MOST detected transits by exoplanet 55 Cancri e of its primary star, based on two weeks of nearly continuous photometric monitoring, confirming an earlier detection of this planet, and allowing investigations into the planet’s composition.In 2019, MOST photometry was used to disprove claims of permanent starspots on the surface of HD 189733 A that were alleged to be caused by interactions between the magnetic fields of the star and its “hot Jupiter” exoplanet.ConclusionIn 2008, the MOST Satellite Project Team won the Canadian Aeronautics and Space Institute’s Alouette Award, which recognizes outstanding contributions to advancement in Canadian space technology, applications, science or engineering.In October 2014, the MOST Satellite was acquired by MSCI, which then commenced commercial operation of the satellite, offering a variety of potential uses including continuing the original MOST mission in partnership with Dr. Matthews, but also other planetary studies, attitude control system algorithm R&D, and Earth observation. MOST was finally decommissioned in March 2019, after an apparent failure of its power subsystem.Refrences The MOST Space Telescope - Astro-Canada MOST (spacecraft) - Wikipedia MOST - A tiny satellite probes the mysteries of the universe - Canadian Space Agency MOST: Mission - UTIAS SFL MOST Specifications - Microsat Systems Canada " } , { "title": "Gravitational Waves", "url": "http://blog.sedscelestia.org/Gravitational-Waves/", "date": "August 21, 2022", "category": "Science", "tags": ["Science","Physics","Astronomy"], "author": "Srikanth C P", "content": "On one fine day in 1916, Albert Einstein decided to completely rewrite our understanding of the physical world when he published his General Theory of Relativity. His findings would forever change our understanding of space and time and completely redefine our understanding of the force of gravity. In order to get into gravitational waves, it is first necessary that we have a very basic understanding of this world-changing theorem.Simply said General Relativity is a theory of gravity. Instead of treating gravity as an invisible force that attracts objects to each other, it is instead the warping of space itself. The heavier the object the more it warps the space surrounding it.Massive Objects Wrap SpaceCredits: ScienceNewsWith this understanding, we are now ready to talk about gravitational waves.Gravitational waves are essentially ripples in the fabric of space-time itself. Einstein’s theorems predict that massive accelerating objects (like neutron stars or black holes orbiting each other) would send waves of rippling space-time outward in all directions. (Picture the ripples created by dropping a stone onto the still surface of a lake). Now the logical question is, why are Gravitational Waves so important? Well, these gravitational waves travel across the universe at the speed of light. Their study reveals information regarding their origin as well as helps in understanding the very nature of gravity itself. As our technology improves, scientists theorise, that we could trace back these waves to their origin, giving us a way to unravel some of the deepest scientific mysteries regarding the expanding universe. Einstein predicted the existence of gravitational waves nearly a century ago but it was only very recently, on September 14th of 2015, that their existence was physically detected. They were detected by LIGO (Laser Interferometer Gravitational-Wave Observatory). By the time gravitational waves reach earth they are over a billion times weaker than when they originated, creating less disturbance than the movement of an atom’s nucleus. LIGO is capable of measuring these tiny disturbances. Currently, there are 2 LIGOs on earth, in Massachusetts and California, USA. However, you will be excited to know LIGO- India is already under work, to be part of a wider network of Observatories all over the globe.The future of Astronomy and modern science is one of hope and wonder. I hope you’re all as excited as I am for what is to come.REFERENCES What are Gravitational Waves? - LIGO Lab - Caltech Gravitational Waves - Wikipedia" } , { "title": "INTEGRAL", "url": "http://blog.sedscelestia.org/INTEGRAL/", "date": "August 2, 2022", "category": "Telescopes", "tags": ["Space_Tech","Technology_in_Space","Science","Telescope-Series","Astronomy"], "author": "Tanmayee Srinivas", "content": "INTEGRAL or INTErnational Gamma-Ray Astrophysics Laboratory was launched in Earth orbit in 2002 by the European Space Agency (ESA) and is used to observe gamma rays of energies up to 8 MeV, X-rays and visible light. It is the most sensitive gamma-ray observatory in space. It was launched from the Russian Baikonur spaceport in Kazakhstan aboard a Proton-DM2 rocket. It is mainly an ESA mission with additional contributions from Italy, France, Germany and Spain. Russian Space Agency with IKI (military CP Comand Punkt KW) and NASA are principal collaborators on this project.MISSIONThe INTEGRAL space observatory is dedicated to fine spectroscopy and fine imaging of celestial gamma-ray sources in the energy range 15 keV to 10 MeV with concurrent source monitoring in the X-ray and optical (V-band) energy ranges. Gamma-ray astronomy looks at the most energetic phenomena and addresses particular fundamental physics and astrophysics problems. The scientific goals of INTEGRAL will be attained by fine spectroscopy with imaging and accurate positioning of celestial sources of gamma-ray vision. INTEGRAL is the first of its kind. Its principal targets are gamma-ray bursts, powerful phenomena such as supernova explosions and regions in the universe thought to contain black holes. Gamma rays do not pass through the Earth’s atmosphere and can only be detected from above the atmosphere.INTEGRAL is the most potent gamma-ray observatory launched and can detect radiation from events far away and processes that shape the Universe. It studies explosions, radiation, formation of elements, black holes and other exotic objects and contributes to multi-messenger astronomy, detecting gamma rays from the first merger of 2 neutron stars observed in gravitational waves and from a fast radio burst.INSTRUMENTSINTEGRAL stands 5 m high and weighs more than 4 tonnes in weight. It has two main parts: the service module and the payload module. The service module is the lower part and contains all spacecraft subsystems to support the mission. To limit the cost of the mission, this module was a rebuild of the one developed for XMM_Newton. It is a closed structure of a combination of aluminium and carbon fibre. It holds the satellite systems, including solar power generation, power conditioning and control, data handling, telecommunications and thermal. Altitude and orbit control. The payload module is mounted on the service module and carries the scientific instruments. This is composed of 4 scientific instruments weighing 2 tonnes, making it the heaviest payload placed in orbit by ESA. the detectors’ have a large area required to capture sparse and penetrating gamma rays. These instruments have a large field view and are co-aligned on a platform to study targets on a wide energy range. The INTEGRAL imager, IBIS (Imager onboard the INTEGRAL Satellite), observes in the range of 15 keV to 10 MeV. It has an angular resolution of 12 arcmins and a 95X95 mask of rectangular tungsten tiles sittin3.2 m above the detectors. This imaging system is based on 2 independent solid state detector arrays optimised for low and high energies surrounded by an active VETO system ensuring substantial reduction of the background due to induced photon and hardonic components, enhancing detector sensitivity. The imaging device is a Tungsten Coded Aperture Mask (16 mm thick and ~1 squared meter in dimension). First astronomical image (17 November 2002) from Cygnus X-1IBIS (ISGRI) image, (40-100) keV, ~ 30 min exposure.Credits: ESA SPI, or the SPectrometer of INTEGRAL, was created and assembled by the French Space Agency CNES, with PI institutes in Toulouse/ France and Garching/ Germany. It has hexagonal tungsten tiles coded mask above a detector plane of 19 germanium crystals (hexagonally packed). It observes radiation in the range of 20 keV and 8 MeV, and the high energy resolution of 2 keV and 1 MeVresolves all candidate gamma-ray lines. The Ge crystals are rapidly cooled with Stirling coolers to about 80K. First astronomical image (17 November) from Cygnus X-1SPI image (25 - 45) keV, ~ 60 min exposureCredits: ESA Dual JEM-X (Joint European X-Ray Monitor) units provide information on sources at hard and soft X-rays. They not only broaden the spectral coverage they also provide for more precise imaging due to shorter wavelengths. First deconvolved image from JEM-X. Since the pointing was done on a practically empty field, with just a few very weak sources, no sources are detected in the ~ 2000 sec exposure. The Optical monitor instrument, or OMC, is sensitive from 500-580 nm. It is mounted close to the top of the payload module structure. With the help of the X-Ray Monitor JEM-X, optical emissions from the primary targets of the INTEGRAL main gamma-ray sensors are observed. First light image from the optical monitor camera OMC on-board INTEGRAL. Credits: ESA INTEGRAL Radiation Environment Monitor or IREM notes the orbital background for calibration purposes. It senses radiations up to cosmic rays, and if the background exceeds a preset threshold, IREM shuts down instruments. Radiation monitor IREM data of Proton fluxes during early revolutions. Credits: ESAORBITINTEGRAL orbits the Earth in a 3-day elliptical orbit. It is placed at an altitude higher than 60,000 km to avoid the effects of background radiation. The lowest point is 9000 km, and the highest is 153000 km. The high and unusual orbit ensures extended periods of continuous observation with background radiation that is almost constant and free of radiation trapped in Earth’s proton and electron belts. The 72-hour-long orbital period guarantees optimal coverage pattern from the ground stations. This allows for repeated working shifts on the ground as the coverage is constant for INTEGRAL’s orbit for all revolutions.INTEGRAL orbit.Credits: ESAUNIQUE SELLING POINTINTEGRAL is meant to help discover more about the element-making process during the death of a star.The events that made the universe habitable were cataclysmic. Violent stellar explosions were the source of the energy that was required to form elements that created planets and living beings. Gamma rays from these explosions are recorded by INTEGRAL.Intense gamma rays from the black hole at the centre of the milky way galaxy are registered, and results from INTEGRAL may help understand this object’s nature. Gamma rays are also observed when matter squirms in the powerful gravity of a collapsed and very dense remnant of a star after a supernova explosion. Studying black holes or neutron stars, or other compact objects.INTEGRAL may also find evidence of bigger specimens of dense objects such as giant black holes and allow detailed studies of the physical properties of such things.DISCOVERIESSo far, INTEGRAL has mapped the sky in the 511 keV emission line from the electron-positron annihilation and found that the emission is concentrated in the centre of the milky way. It has also found a faint population of gamma-ray bursts concentrated toward nearby superclusters.It has also found what seems to be a new class of astronomical objects. These are binary systems with the possibility of including a black hole or neutron star embedded within a cocoon of cold gas. On analysis, it was observed that this was a binary system with a compact object and a ginormous companion star, and the cocooning material is probably stellar wind (gas ejected by the companion star). This object was then named IGRJ16318-4848 and was discovered on 29th January 2003.INTEGRAL is also credited with the discoveries of X-ray binaries, active galactic nuclei, cosmic x-ray backgrounds, and gamma-ray bursts. It has also detected polarised emissions in 3 sources observed by INTEGRAL.CONCLUSIONThe INTEGRAL space telescope was initially supposed to be a 5-year mission that got extended and has now been running for almost 20 years. In July 2020, the mission faced a setback that nearly caused the ESA to lose the space telescope. The failure of a minor, significant part of the telescope caused it to spin out of control and prevented the solar panels from generating power. The Emergency Safe Attitude Mode had been activated but proved ineffective due to a failure in the thrusters.The team could reactivate the malfunctioning wheel, but the spacecraft did not regain its balance and kept wobbling about its axis. They initially gained control for a bit after turning off noncritical components and sending commands to the reaction wheels so they would stop spinning. But, they lost control again, presumably due to the Earth blocking the INTEGRAL’s view of the stars it uses to orient itself. Corrective actions were repeated, and the spin was repaired again.The spacecraft is back in orbit and has outlived its initial runtime by over a decade. It is “living long and prospering” and will continue to help unravel some of the mysteries of the universe.REFERENCES INTEGRAL - Wikipedia ESA - Integral overview The INTEGRAL Mission - AandA.org (PDF) IBIS: the imager on-board INTEGRAL Instruments SPI - INTEGRAL Instruments JEMX - INTEGRAL. INTEGRAL Radiation Environment Monitor (IREM) ESA’s Integral discovers hidden black holes Darmstadt, we have a problem – ESA reveals its INTEGRAL space telescope was three hours from likely deathHeader Image Credits: INTEGRAL [artist impression]. Credits: ESA" } , { "title": "Chandra Space Observatory", "url": "http://blog.sedscelestia.org/Chandra-Space-Observatory/", "date": "July 19, 2022", "category": "Telescopes", "tags": ["Space_Tech","Technology_in_Space","Science","Telescope-Series","Astronomy"], "author": "Nirmal Govindaraj", "content": "What is the Chandra observatory?The Chandra X-ray observatory is one of NASA’s Great Observatories sharing the title with the likes of Hubble. It helps scientists in the field of X-ray astronomy (using X-rays to study and answer fundamental questions about the nature of our universe). It is the largest and most sophisticated X-ray telescope ever built and one of NASA’s most successful missions.Image creds - Chandra Image Gallery | NASABackgroundThe Chandra telescope was named after the Nobel laureate and astrophysicist Subrahmanyan Chandrasekhar, who was widely regarded as one of the foremost astrophysicists of the 20th century.He is most notable for the Chandrasekhar limit, which gives the maximum mass of white dwarf stars( 1.44 Solar mass). He showed that any white dwarf beyond this mass would collapse into a neutron star or black hole. This discovery is one of the foundations of modern astronomy.Image credits - S. Chandrasekhar - Biography, Discoveries, Nobel Prize, Accomplishments, & Facts - BritannicaX-ray AstronomyX-ray astronomy uses X-rays to study the high-energy parts of the universe, and using X-rays often helps us explore these events in much better resolution.Image credits - About Chandra :: Chandra MissionX-rays are produced in the cosmos when matter is heated to millions of degrees. This is why they are usually found in our universe’s high-energy regions, such as the remnants of exploded stars. They also help us discover vast clouds of hot gas and supernova remnants and even study matter swirling around a black hole.To celebrate the 15th anniversary of NASA’s Chandra X-ray Observatory, four new images of supernova remnants are being released. These spectacular cosmic vistas are the glowing debris fields that were created when massive stars exploded at the ends of their lives.Image credits - NASAA vast majority of X-rays are absorbed by the Earth’s atmosphere, which is why space-based telescopes like Chandra are required to make these observations.About the ObservatoryChandra was launched in 1999, aboard the space shuttle Columbia, for what was initially planned to be a 5-year mission. But due to its outstanding results, the mission was extended and is still going strong even today.The observatory has 3 main parts: The X-ray telescope comprises unique, extremely smooth mirrors that focus X-rays from celestial objects. The resolution is so powerful that it’s equivalent to reading a stop sign 12 miles away! The science instruments record and analyse the data to produce images. The spacecraft itself provides the environment for the instruments to work. It consists of thrusters to help control its orbit and solar arrays, which provide the power for the systems. It produces 2 kilowatts of power which is about the same as that of a hair dryer.Image credits - Chandra :: Resources :: Spacecraft :: Artist’s IllustrationsChandra is in an elliptical orbit whose zenith takes about a third as far as the distance from the Earth to the Moon. It has a 64-hour orbit, but due to its highly elliptical orbit, it can observe continuously for up to 55 hours. Due to the high Earth orbit majority of the time, it remains unaffected by the charged particle belt surrounding Earth.Exciting discoveries made by ChandraGigantic Cloud of gas surrounding the Milky wayIn 2012 Chandra provided evidence for an enormous halo of hot gas surrounding the milky way with an estimated radius of 300,000 light years. Scientists estimated that the temperature of the gas could be between 1 million and 2.5 million kelvin, and its mass comparable to all the stars in the Milky Way.If the size and mass are confirmed it could solve the missing Baryon problem for our galaxy.This artist’s illustration shows an enormous halo of hot gas (in blue) around the Milky Way galaxy. Also shown, to the lower left of the Milky Way, are the Small and Large Magellanic Clouds, two small neighboring galaxies. The halo of gas is shown with a radius of about 300,000 light years, although it may extend significantly further.Image credits - NASA/CXC/M.Weiss; NASA/CXC/Ohio State/A Gupta et alBaryonic matter (Protons and Neutrons) makes up the observable universe but for a long time, scientists have known that only half of all the Baryonic matter is accounted for. One idea is that the missing Baryons are part of a highly diffuse network of gas clouds. The best way to detect them is through their faint X-ray signatures, which Chandra can do.Mega merger of 4 galaxy clustersChandra and other telescopes observed a mega merger of 4 galaxy clusters in Abell 1758. A galaxy cluster is a massive collection of galaxies all gravitationally bound to each other and embedded in hot gas. They are some of the largest objects in the universe.Labeled image of Abell 1758 system.Image credits - Chandra :: Photo Album :: Abell 1758 :: October 24, 2019Abell 1758 located 3 billion light years away, contains 2 pairs of galaxy clusters on their way to collide. Each pair contains two galaxy clusters already well on their way to merging.Once merged, this quadruple galaxy cluster system will form one of the most massive objects in the known universe.Large spinning Black holeAnother recent discovery released in 2022 was a massive spinning black hole located 3.4 billion light years from Earth. H1821 + 643 is a Quasar powered by a supermassive black hole with an estimated mass between 3 and 30 billion solar masses making it one of the largest black holes we know of. X-ray observations from Chandra showed that the black hole is spinning at around half the speed of light!Chandra Shows Giant Black Hole Spins Slower Than Its PeersImage credits - Chandra Image Gallery - NASAConclusionThe Chandra X-ray observatory has been one of NASA’s most successful missions till now. What Chandra has done for X-ray astronomy is arguably the same as what Hubble did for optical astronomy.It gave us spectacular images of cosmic phenomena and glimpses into some of the most extreme regions in the universe.Chandra has been invaluable to the field of astronomy in answering many questions about the universe and will continue to do so in the foreseeable future.REFERENCES Chandra X-Ray Observatory: Space Telescope Reveals the Invisible Universe Chandra X-ray Observatory - Wikipedia Chandra X-ray Observatory Chandra :: Photo Album Chandra Overview - NASA NASA’s Chandra Shows Milky Way is Surrounded by Halo of Hot Gas - NASA" } , { "title": "SOHO", "url": "http://blog.sedscelestia.org/SOHO/", "date": "July 12, 2022", "category": "Telescopes", "tags": ["Space_Tech","Technology_in_Space","Science","Telescope-Series","Astronomy"], "author": "Tanmayee Srinivas", "content": "On 2nd December 1995, the European Space Agency (ESA) launched the Solar and Heliospheric Observatory(SOHO) as a joint operation with the National Aeronautics and Space Administration(NASA) to study the sun. It was launched on the Lockheed Martin Atlas IIAS launch vehicle and was designed to study the sun inside-out. It was meant to operate till 1998, but its success encouraged NASA and ESA to support many mission extensions, allowing it to cover 11 periods of solar activity. SOHO was a part of the International Solar-Terrestrial Physics Program and continues to operate after over 25 years in space and has been extended until the end of 2025.SOHO on the Atlas II-AS (AC-121), Cape Canaveral Air Station, 2 December 1995.Credits: NASASOHO is also the primary source of near-real-time solar data for space weather predictions. It is near the Earth-Sun L1 point (0.99 astronomical units(AU) from the sun; 0.01 AU from the earth). It is also the first three-axis-stabilised spacecraft to use its reaction wheels as a virtual gyroscope which was adopted in 1998 after an accident which nearly resulted in the loss of the spacecraft.Spacecraft illustration.Credits: Alex LutkusOBJECTIVESSOHO was created for three main objectives: Investigation of the outer layer of the sun Making observations of solar wind and associated phenomena in the L1 vicinity Probing the interior of the sun (helioseismology)INSTRUMENTSTo achieve its goals, SOHO carries a payload of 12 complementary instruments. It is an 1850 kg spacecraft powered by solar panels delivering \\(1150 W\\). The payload weighs \\(650 kg\\) and has a \\(500 W\\) power consumption. Each instrument is capable of independent or coordinated observation of the sun and spacecraft components. The instruments are: Coronal diagnostic spectrometer (CDS): Designed to detect solar ultraviolet radiations to study the conditions in the solar corona(the outermost part of the sun’s atmosphere). The data recorded gives information on temperature, density, elemental composition and flows of the plasma in the sun’s magnetic field. Charge Element and Isotope Analysis System (CELIAS): Detects solar winds (stream of energised, charged particles, primarily electrons and protons, flowing outward from the Sun) and analyses the density and nature of the charged particles in it. It warns about incoming solar winds, which reach SOHO \\(30-60 minutes\\) before they reach the Earth. Includes \\(33\\) mass and charge-discriminating sensors: charge time of flight (CTOF), mass time of flight (MTOF), and suprathermal time of flight (STOF). Comprehensive SupraThermal and Energetic Particle Analyser collaboration (COSTEP): Consists of 2 instruments: Electron Proton Helium Instrument (EPHIN) and Low Energy Ion and Electron Instrument (LION). Both instruments measure energetic particles emitted by the sun, studying the ionic composition of the solar winds. Extreme ultraviolet Imaging Telescope (EIT): Used to obtain high-resolution images of the solar corona in the ultraviolet range. It is sensitive to light of four wavelengths corresponding to highly ionised iron (XI)/(X), (XII), (XV), and helium (II). it is a single telescope with a quadrant structure to mirrors, and each quadrant reflects a different colour of EUV light. It studies low coronal structure and activity. Energetic and Relativistic Nuclei and Electron experiment (ERNE): Also studies the electron and ion composition of solar winds. In the absence of solar winds, ERNE observes galactic cosmic rays from the milky way and analomous cosmic rays from the boundary of the heliosphere accelerated by termination shock. COSTEP and ERNE are sometimes referred to as COSTEP-ERNE Particle Analyser Collaboration Global Oscillations at Low Frequencies (GOLF): Studies the internal sun structure by measuring oscillations from \\(10^-7\\) to \\(10^-2\\) Hz. It studies velocity variations of the entire solar disk to study the sun’s core. Large Angles and Spectrometric Coronagraph (LASCO): Creates an artificial eclipse to study the corona. It consists of three coronagraphs: C1 (Fabry Perot etalon, imaging \\(1.1\\) to \\(3\\) solar radii), C2 (white light coronagraph, imaging \\(1.5\\) to \\(6\\) solar radii) and C3 (white light coronagraph, imaging \\(3.7\\) to \\(30\\) solar radii). Michelson Doppler Imager (MDI): Measures velocity and magnetic fields in the lowest layer of the sun’s atmosphere (photosphere) to understand the convection zone (outermost layer of the solar interior) of the sun. It also concerns the study of the fields that give structure to the sun’s corona. Solar Ultraviolet Measurement of Emitted Radiation (SUMER): Delivers research data about the solar atmosphere; measures plasma flows, temperature and density in the solar corona. Solar Wind Anisotropies (SWAN): uses a telescope sensitive to characteristic hydrogen wavelengths to observe the solar Lyman alpha photons backscattered by the neutral hydrogen atoms in the interplanetary medium. It sees ultraviolet rays across interplanetary gas beyond the sun. UltraViolet Coronagraph Spectrometer (UVCS): Has three reflecting telescopes with external and internal occultation, a visible polarimeter and two toric grating spectrometers integrating into a spectrometer. It provides data that can address several questions about the nature of the solar corona and the generation of the solar wind. Variability of solar IRradiance and Gravity Oscillations (VIRGO): Probes the Sun’s core again by monitoring solar oscillations and the solar constant over the whole solar disc and at low resolution.CDS, EIT, LASCO, SUMER, SWAN, and UVCS, are used for this solar atmosphere remote sensing. CELIAS and COSTEP are used for “in situ” solar wind observations. GOLF, MDI, and VIRGO are used for helioseismology.DISCOVERIESSOHO provided the first images of the sun’s convection zone and of sunspots below the surface. It has provided detailed measurements of solar winds, event identifying source regions and acceleration mechanisms. It has also helped in monitoring eruptions from the sun that cause effects on the earth. It has improved the accuracy in forecasting geomagnetic disturbances and has shown early-warning capabilities for space weather. The mission has also discovered 4000 new comets and new solar phenomena like coronal waves and solar tornadoes.EIT full sun images in Fe XII 195 A (left), Fe IX/X 171 A (middle), and the ratio of these two images (right). The latter one gives an indication of the temperature distribution in the Sun’s corona with dark areas being cooler regions and bright areas being hotter.Credits: NASAHuge sunspot group – Active region 9393 as seen by MDI hosted the largest sunspot group observed so far during the current solar cycle.Credits: NASAORBITSOHO orbits at the first Lagrangian point L1 on the Earth-Sun line. At this point, the balance of the Earth’s gravity and the Sun’s gravity equals the centripetal force needed for an object to have the same orbital period around the sun and earth.But the SOHO spacecraft is not exactly at L1 as this causes communication issues due to radio interference generated by the sun and lack of stable orbit. Instead, it lies on the plane which passes through L1 and is perpendicular to the line connecting the sun and the earth, tracing out an elliptical halo orbit centred about L1.SOHO moves around the Sun in step with the Earth, by slowly orbiting around the First Lagrangian Point (L1), where the combined gravity of the Earth and Sun keep SOHO in an orbit locked to the Earth-Sun line. The L1 point is approximately 1.5 million kilometers away from Earth (about four times the distance of the Moon), in the direction of the Sun. There, SOHO enjoys an uninterrupted view of our daylight star. All previous solar observatories have orbited the Earth, from where their observations were periodically interrupted as our planet `eclipsed’ the Sun.Credits: NASALOSS OF SOHOIn June 1998, all contact with SOHO was lost. After weeks of silence, in August 1998, a powerful radar signal from Earth produced a faint echo from the spacecraft. As luck would have it, the spacecraft was still in the right place and sunlight would soon fall on its solar cells again, enabling it to resume operations. Other difficulties were presented in the form of loss of gyroscopes to control spacecraft orientation. An inquiry was set and it was concluded that the loss of SOHO was mainly due to ground errors rather than on board anomalies. It was a direct result of operational errors, a failure to monitor spacecraft status and a imprecise decision which disabled part of the onboard autonomous failure detection.After initial recovery,with only a single gyro operational, it was decided to push forth the ideation of a gyroless modeland on February 1st 1999, SOHO became the first three-axis-stabilised ESA spacecraft to be operated without a gyroscope.CONCLUSIONAfter 25 years in space, SOHO has observed and provided a deeper insight into our sun on longer timescales. The star flips its magnetic polarity every 22 years and ramps up and down in activity every 11 years. SOHO has been able to observe both cycles completely. SOHO’s EIT has also observed several wavelengths of light that our impossible to observe from the Earth due to the atmosphere. SOHO was also the source of higher resolution data inspiring several other mission proposals. In addition to advancements in solar science, SOHO’s LASCO has discovered several comets too, most by citizen scientists and amateur astronomers who could access this data on the internet.SOHO remains an unparalleled reservoir of ongoing data even with advancements in technology. It is an extremely ambitious mission according to the current US Project Scientist, Jack Ireland. He believes that if anything, SOHO is highly likely to do a complete breakdown of our sun and it’s workings. The originally planned three year mission completes 27 years this year will remain the best possible source of solar data in the near future.Solar Wind and the Earth’s Protective Magnetic Shield illustration.Credits: NASAREFERENCES Solar and Heliospheric Observatory - Wikipedia Solar and Heliospheric Observatory Heliosphere Extreme ultraviolet Imaging Telescope - Wikipedia https://web.archive.org/web/19991009161459/http://golfwww.medoc-ias.u-psud.fr/ SOHO MISSION INTERRUPTION FAILURE INVESTIGATION ESA - SOHO overview SOHO’s Recovery – An Unprecedented Success Story SOHO Mission Celebrates a Quarter-Century in Space - NASAHeader Image Credits: NASA" } , { "title": "Space Debris", "url": "http://blog.sedscelestia.org/Space-Debris/", "date": "June 25, 2022", "category": "Astronomy", "tags": ["Space_Tech","Technology_in_Space"], "author": "Dhruv Parashar", "content": "Space debris refers to the junk or waste in space, including waste left by human beings as part of space exploration missions and naturally in the form of meteoroids. Dead satellites, the fragmentation pieces of rocket equipment, paint speckles, unburnt particles from solid rocket motors etc., all contribute to the space debris.The diameter of space debris may be even smaller than 1 cm. As of January 2019, more than 128 million pieces of debris smaller than 1 cm (0.4 in), about 900,000 pieces 1–10 cm, and around 34,000 pieces larger than 10 cm (3.9 in) were estimated to be in orbit around the Earth.Space debris may seem to be a trivial issue, but it isn’t. Space debris affects a lot of calculations done while preparing for a space mission. Even the smallest of litter mayput the whole mission in jeopardy.Fortunately, space debris has not fatally affected anyone yet. There was one incident in Tulsa, Oklahoma, U.S, in 1997. A lady, Lottie Williams, was walking in the park in the morning when she saw an astronomical body in the sky, which she felt was a shooting star. Some minutes later, it hit her shoulder tenderly. After research, it was found that it was part of a fuel tank from a Delta II rocket launched by the US Air Force a year before.Even though no space mishaps have been credited to space debris, space debris will make future explorations a tedious task. There are more than 3000 dead satellites in space. 34,000 pieces of space junk larger than 10 centimetres exist in the space. Moreover, the ISS has done 25 debris avoidance manoeuvres since 1999. All of this will shoot up further, given the scale and frequency of satellite launches we are witnessing currently.There is another stark fact related to the space debris, which is that it grows exponentially, as some fragments of debris collide with others to divide further to form more particles.If humans are to dive into space exploration further, finding a solution to remove space debris is imperative. It cannot be disregarded.Even though space agencies across the globe are racing against time to remove space debris, there is no sustainable and implementable solution in sight yet. Some of the methods which have been proposed are:1) Snagging and Moving Space Junk:This method involves capture mechanisms like robotic arms, tentacles, nets, harpoons etc. Deorbit was a planned European Space Agency active space debris removal mission developed as a part of their Clean Space initiative. The launch was expected to take place in 2025.But now the ESA has stopped funding to this project and have started funding ClearSpace-One. This mission has also inculcated the capture mechanism inspired by animals.Image Credit- WikipediaA computer-generated image representing the locations, but not relative sizes, of space debris as could be seen from high Earth orbit. The two main debris fields are the ring of objects in geosynchronous Earth orbit (GEO) and the cloud of objects in low Earth orbit (LEO).2) Pushing Debris Out of Space:This is the ClearSpace-One project of ESA. Launch is planned in 2025. This also works on the gripping mechanism. Finally, once coupled with the satellite, CleanSpace One will “de-orbit” the unwanted satellite by heading back into the Earth’s atmosphere, where the two satellites will burn upon re-entry.Image Src: KurzweilCleanSpace One (credit: EPFL)3) Using the Power of Electricity:This was essentially a fishnet-inspired mission. The Japan Aerospace Exploration Agency (JAXA) aimed to employ a fishnet mechanism using electrodynamic tethering, which would decrease the speed of revolution of old and unused satellites. This would lead them to fall into the lower orbit of Earth which would burn them up completely. Unfortunately, this mission failed the first test as it could not deploy the electrodynamic tether.5) Huffing and Puffing:Now, scientists are considering a huff-and-puff approach to remove debris from orbit by firing focused pulses of atmospheric gases into the path of targeted space trash.That’s the idea behind SpaDE, a Space Debris Elimination initiative by Daniel Gregory of Raytheon BBN Technologies in Virginia. Vertical bursts of air produced within Earth’s atmosphere can either be directed at orbiting riffraff to change its trajectory or cause drag on the clutter to hasten its re-entry.Image Credit: SPACE.com6) Sail method:The activity is developing a subsystem that will recognise as soon as the satellite has come to the end of its mission has failed, for example, if it has had no signal for a month. It will then slowly unfurl a large aluminium-coated polyamide membrane attached to four carbon-fibre-reinforced booms. This membrane acts as a sail to create a drag effect causing the spacecraft to decrease its orbit much faster, catching at the atmosphere to slow the worn-out spacecraft enough that it will burn up entirely. A process that can take quite long, depending on the spacecraft – up to 25 years.7) Knock Junk Down with a Net:A network of nanosatellites, connected with a piece of electrically conducting tape that could be as long as 2 miles (3 kilometers), could knock satellites down as it passes through Earth’s magnetic field and produces voltage. The solar-powered ElectroDynamic Debris Eliminator (proposed by Star Technology and Research, Inc.) could eliminate all large pieces of satellite debris in low-Earth orbit within a dozen years.Image credits-NASA8) Project NETRA:ISRO’s work on space junk is in the initial phase. ISRO launched project NETRA. ‘Project NETRA’ is an early warning system to detect debris and other hazards to Indian satellites.Under NETRA, the ISRO plans to establish many observational facilities: connected radars, telescopes, data processing units and a control centre. NETRA can spot, track and catalogue objects as small as 10 cm, up to a range of 3,400 km and equal to a space orbit of around 2,000 km.India has installed an incredible liquid mirror telescope in the Himalayan range in Nainital, Uttarakhand. The telescope will track space debris and asteroids. It is Asia’s largest such telescope.Image Credits: Times of IndiaCONCLUSIONRemoval of space debris is highly essential for future space exploration missions and poses a massive roadblock in space missions. In a future where humans expect themselves to be a multi-planetary species, we have to ensure that space debris does not become an obstruction.We should shift our focus to ensure that the amount of space debris does not increase. Hence, it is essential to improve our current satellite and rocket-making methods to corroborate a technology where these satellites destroy themselves or bring themselves to the Earth’s orbit to eliminate the possibility of space debris generation in the first place.Removal of space debris is a significant priority for all agencies today. Let us hope that there will be a few sustainable solutions in the coming times which will help us get rid of it so that space exploration can go on in the future in a hassle-free way and our precious ‘Space’ does not become a junkyard.Image Credits: Florida TodayREFERENCES Progress 59 spacecraft: what are your chances of being hit by falling debris? - Space - The Guardian. What is space junk and why is it a problem? How to Clean Up Space Junk - Spaceaustralia Space Junk Clean Up: 7 Wild Ways to Destroy Orbital Debris CleanSpace One Satellite Will Remove Space Debris. ClearSpace-1 - Wikipedia Gallery: Space Junk Cleanup by CleanSpace One Satellite Japan goes fishing for space junk but 700-metre ‘tether’ fails Solar-Propelled Invention Designed to Clean Up Space Trash - Embry-Riddle Aeronautical University - Newsroom ESA - Sail solutions for space junk How Huffing and Puffing Could Remove Space Junk Space debris - Wikipedia India sets up unique telescope in Himalayan range to keep watch on space debris and asteroids CleanSpace One: Swiss satellite to tackle risky space debris15.e.Deorbit - Wikipedia NETRA Project & Space JunkHeader Image Credits: johan63/iStock/Getty Images Plus" } , { "title": "Hubble Space Telescope", "url": "http://blog.sedscelestia.org/Hubble-Space-Telescope/", "date": "June 21, 2022", "category": "Telescopes", "tags": ["Science","Telescope-Series","Astronomy"], "author": "Sunayana S Moro", "content": "Try and think of the most beautiful and detailed image you’ve seen of galaxies or any deep space object for that matter, there’s a good chance that the picture was taken by the Hubble space telescope. The Hubble space telescope has given what is arguably some of the most important contributions to our study of the universe.Space telescopes have two main advantages over ground-based telescopes. First, the resolutions at which scientists could observe would increase significantly as there would be no disturbance due to the turbulence caused by the atmosphere. Second, the telescope could observe infrared and ultraviolet rays ( most of these rays are usually absorbed by the atmosphere).While ideas for space telescopes existed from as early as 1945, they did not gain any support until the The National Academy of Sciences published a report entitled “Scientific Uses of the Large Space Telescope.” It took 8 whole years for the project to gain momentum until it finally got congress approval and funding in 1977. The image shows the main structure of the Hubble space telescope as it is currently. Given its length, one of the main challenges of launching the Hubble space telescope was to make sure that it would stay stable, and this was solved using 6 of the most sensitively tuned gyroscopes.This shows a cross-section of the NASA/ESA Hubble Space Telescope (HST). The radial instrument bay is seen in yellow, the axial instrument bay in red, the primary and secondary mirrors in blue, and the optical equipment in green.Credit: ESAAfter 20 years of hard work, almost two billion dollars, and hundreds of technical, financial, and political hurdles later, the Hubble space telescope was launched into space in 1990. While the launch was successful, NASA later found out that the primary mirror was slightly chromatically aberred, the edges of the primary mirror were ground slightly flatter( by about 0.0022 mm), which created these fuzzy halos around objects. While the other launch and the the multi-million dollar equipment worked well, this small error made the hubble pretty much useless for almost 3 years. NASA and ESA engineers together designed a solution- COSTAR. COSTAR was an instrument built with five pairs of small mirrors on motorised arms. COSTAR would essentially act something like corrective glasses that we use to focus light accurately. This repair was not easy, the many technical challenges which came along with it forced NASA to send a crew of astronauts to fix it. The astronauts replaced the high speed photometer with COSTAR. To this day astronaut who replaced it- Kathryn Thronton believes that it was a miracle it worked and that they could have just as easily killed it. 11 days of calibrations later, the Hubble came out with the most stunning, detailed beautiful pictures ever taken, with each pixel of the picture holding a mystery to be solved. As expensive as the repair was, the intricacy of the pictures was so remarkable, you’d forget all about it. These images are not just breathtaking, but every single point in these pictures contained the answers to the mysteries of the universe.Src: HubblesiteComparison of a WFPC2 thermal vacuum globular cluster-mask image to WFPC1This Hubble Space Telescope (HST) image shows rich detail, previously only seen in neighboring star birth regions, in a pair of star clusters 166,000 light-years away in the Large Magellanic Cloud (LMC), in the southern constellation Doradus. The field of view is 130 light-years across and was taken with the Wide Field Planetary Camera 2.Credit: R. Gilmozzi, Space Telescope Science Institute/European Space Agency;Shawn Ewald, JPL; and NASAA NASA/ESA Hubble Space Telescope image of a region of the Great Nebula in Orion, as imaged by the Wale Field Planetary Camera 2.Hubble Probes the Great Orion NebulaThe pictures taken by Hubble have lead to some of the most important breakthroughs in Astronomy, and have helped answer questions about the state of our universe. The most important among them being helping us understand the expansion and the age of the universe, this was one of the major scientific justifications for building the Hubble Space Telescope.A bit of background, in 1924, Edwin Hubble(If you hadn’t guessed already, the telescope is named after him) observed that galaxies were moving away from each other, and long story short it was concluded that the universe was expanding. In simple terms, if we had an accurate way of measuring the rate at which galaxies moved away from us, we would essentially be able to tell the age of the universe.The Hubble telescope used observations of cepheids to determine the age of the universe, the way this was measured is quite fascinating.Cepheids are a special type of variable star with very stable and predictable brightness variations. The frequency of these changes is determined by the stars’ physical attributes, such as mass and true brightness. This means that we could learn about the Cepheids’ physical nature just by looking at the variability of their intensity of the light, which can then be used to measure their distance. The Cepheids were subsequently employed as stepping stones for measuring the distance between supernovae, which provided a gauge for the Universe’s scale. Using these Cepheid measurements, astronomers could accurately determine the age of the universe to be 13.8 billion years old.This image released in 2016 is just one of the breakthroughs we’ve had. The tiny red spot which is zoomed in is the GN-z11 galaxy, the farthest galaxy known to mankind. It is 13.4 billion years old, which means that we’re seeing the galaxy as it was 13.4 billion years ago. This galaxy is much faster and brighter than what astronomers predicted for galaxies at that time, this one image totally changed our understandings of galaxies in the early universe. We are able to observe and learn how the universe was 13.4 billion years ago from this one single image. In a way, Hubble is a time machine, we’re essentially able to observe how the universe is expanding and how it’s been changing through it.DISTANT GALAXY GN-Z11 IN GOODS NORTH SURVEYHubble Team Breaks Cosmic Distance RecordAnother very interesting Hubble image is the Hubble Deep Field. In 1995, the Hubble pointed at a small, seemingly empty area in Ursa Major, where there was thought to be nothing. Hubble pointed at this tiny area which was only about 2.6 arcminutes, which is about one- 24 millionth of the entire sky for almost a month, this was pretty controversial at the time- to spend precious Hubble time looking at an empty patch? And again, Hubble did not disappoint, the image it produced was spectacular in all ways. This image of a tiny point in a tiny patch in the sky where there seemed to be nothing was covered in galaxies. Every point on the image is a galaxy. We now know that we are surrounded by galaxies in hundreds of billions all around us, in every direction.A few years later, Hubble observed a much deeper field from September 2003 to January 2004, near the constellation Fornax which is in the south hemisphere, south-west of orion. This picture- Hubble Ultra Deep Field(HUDF) was the most sensitive picture taken until the XDF(eXtreme Deep Field) which was released in 2014Full WFPC2 Mosaic - Full ResolutionCredit: R. Williams (STScI), the Hubble Deep Field Team and NASA/ESAHubble sees galaxies galoreCredit: NASA, ESA, and S. Beckwith (STScI) and the HUDF TeamXDFOther than the aforementioned, the Hubble has been behind several other achievements as well. The images provided by Hubble have helped establish the theory that there are blackholes at the center of most galaxies. It has also discovered quite a few solar systems (1st exoplanet was discovered by Hubble in 2008).Hubble has made incredible contributions to Astronomy, with over 15,000 papers based on its data have been published in peer-reviewed journals. While almost 1/3rd of all papers in astronomy go uncited (after many years of publication), 98% of all papers based on Hubble data have citations.It isn’t an exaggeration to say that the Hubble space telescope is one of the most important projects of all time in the field of astronomy.REFERENCES The Hubble Deep Fields The study of exoplanets and proto-planetary discs - ESA/Hubble Hubble Space Telescope - Wikipedia Cepheid variable - Wikipedia Hubble Deep Field - Wikipedia About - Hubble History Timeline - NASA About - Hubble Servicing Missions - NASA GN-z11 - Wikipedia NASA - Hubble Views the Star That Changed the Universe One of the Oldest and Most Distant Objects in the Universe Has Been Discovered - Space Hubble Space Telescope team revives powerful camera instrument after glitch Hubble’s Mirror Flaw - NASA Hubble Takes Major Step in Determining the Age of the Universe Corrective Optics Space Telescope Axial Replacement - Wikipedia History: The Spherical Aberration Problem - ESA/HubbleHeader Image Credits: Hubble telescope orbitting Earth (Getty Images/NASA/dima_zel)" } , { "title": "Cosmic Background Explorer (COBE)", "url": "http://blog.sedscelestia.org/Cosmic-Background-Explorer/", "date": "June 14, 2022", "category": "Telescopes", "tags": ["Science","Telescope-Series","Astronomy"], "author": "Anushka Umarani", "content": "Somewhere, something incredible is waiting to be known.Space exploration has sparked widespread human curiosity ever since its origins. We have used a variety of means to achieve the knowledge that we seek about celestial bodies that surround us. One such means was a satellite called the Cosmic Background Explorer (COBE) or Explorer 66. It was operated by NASA between 1989 and 1993 with the objective of investigating Cosmic Microwave Background (CMB) radiation of the universe and detecting patterns that could help us expand our understanding of the cosmos.This all-sky image of the cosmic microwave background, created from data collected by the European Space Agency’s Planck satellite’s first all-sky survey, shows echoes of the Big Bang left over from the dawn of the universeImage credit: ESA/LFI & HFI ConsortiaWhat is CMB radiation?CMB radiation is the remnant of the Big Bang left over from the dawn of the universe. According to this theory, when the universe was born, it went through rapid inflation before expanding and cooling off. The heat left behind after these changes is represented by the CMB radiation. Dating back to almost 400,000 years after the Big Bang and the time when the universe was opaque to radiation, it is considered to be the oldest known cosmic radiation. It is most visible in the microwave part of the electromagnetic spectrum. The subtle temperature differences we see are linked to the density variations of the early universe. These are also the same variations that are believed to have birthed colorful nebulae, clusters of galaxies and even void spaces that make up our understanding of the night sky.Interestingly, CMB was first discovered by accident in 1965 by Arno Penzias and Robert Wilson even after being predicted by Ralph Apher in 1948! It was detected as a uniform noise from a radio receiver being developed in Bell Telephone Laboratories. Penzias and Wilson later went on to win the Nobel Prize in Physics in 1978.Image Credit: Clive Granger - WikipediaHow did COBE help us map the CMB radiation?Launch and DesignLaunched on November 18, 1989 from Vanderberg Air Force Base, California after years of planning, modeling and engineering, COBE was designed to take accurate readings of and map the diffuse radiation between 1 micrometer and 1 cm spanning the entire celestial surface. The following quantities were accurately measured: The spectrum of 3 K radiation over the range of 100 micrometers to 1 cm. The anisotropy (property of being directionally dependent) of this radiation from 3-10 mm. The angular distribution of diffuse infrared background radiation of CMB at wavelengths between 1-300 micrometers.To curb systematic errors in the measurements and to allow for the observation of zodiac light at various elongation angles, COBE rotated at 1 rpm about its axis of symmetry, oriented 94 degrees to the Sun-Earth line. The instruments inside carried out a complete scan of the celestial sphere periodically every 6 months.Image credits: NASA Spacecraft IconsInstruments in the payloadCOBE carried a Far Infrared Absolute Spectrophotometer (FIRAS), Differential Microwave Radiometer (DMR), Diffuse Infrared Background Experiment (DIRBE).Far Infrared Absolute SpectrophotometerThe role of this instrument was to measure the CMB radiation quantitatively with utmost precision and accuracy. It was a symmetrical polarizing interferometric spectrometer (a device that splits a single beam into two) and was kept open to space and cooled by liquid Helium to avoid self interference. This resulted in an emission at a much lower intensity than the existing CMB radiation.Image credit: ScholarpediaDifferential Microwave RadiometerThis was the primary instrument responsible for mapping the CMBR. It was used to test the theories about CMBR, like the probability of it being equally distributed while possessing slight directional differences. It could measure three distinct frequencies of 31.4 Hz, 53 Hz, and 90 Hz. Maps were produced from millions of measurements of the differences in intensities.Image credit: ScholarpediaDiffuse Infrared Background ExperimentDIBRE was used to survey diffuse infrared sky measurements and submillimeter background light from the first generation galaxies and stars. It was predicted that this diffuse background was emitted in the early universe by objects which are very faint to be visible to the naked eye. It was modeled to reject most of the stray light entering it and hence had a particularly small aperture.Image credit: ScholarpediaThe instrument operations came to a successful end on December 23rd, 1993. COBE provided strong evidence supporting the Big Bang theory’s main aspects: CMB is a near perfect black body spectrum and that it has subtle anisotropies. It mapped the oldest form of radiation in our universe and revolutionized our knowledge of space with its discoveries and paved the way to deeper exploration by WMAP and the Planck mission.AftermathGeorge Smoot and John Manther, the principal investigators of COBE, received the Nobel Prize in Physics in 2006 for their efforts. With its extraordinary results, COBE marked the commencement of cosmology as a precision science and contributed immensely to the studies of spectrum and relics of radiation that linger around long after the Big Bang.Image credit: NASA Scientist Shares Nobel Prize for PhysicsREFERENCES Cosmic Background Explorer - Wikipedia [COBE Science Mission Directorate](https://science.nasa.gov/missions/cobe) [What is the cosmic microwave background? Space](https://www.space.com/33892-cosmic-microwave-background.html) COBE Slide Set - Cosmic Background ExplorerHeader Image Credits: NASASpecial credits for content: Shreeyash Gowaikar" } , { "title": "Space Telescopes: Introduction", "url": "http://blog.sedscelestia.org/Space-Telescopes-Introduction/", "date": "June 7, 2022", "category": "Telescopes", "tags": ["Science","Telescope-Series","Astronomy"], "author": "Shlok Kakkar", "content": "The meaning being derived from the name itself, a space telescope or space observatory is a telescope used to observe astronomical/celestial objects but is placed in outer space. Space telescopes are mainly divided into two types. The first type involves satellites that map the entire sky and are used primarily for astronomical survey purposes. The second type includes those telescopes which focus, study and collect data on specific celestial objects or parts of the sky.The Hubble Space Telescope was launched into Earth’s orbit in 1990, over 25 years ago. The Spitzer Space Telescope, Hubble’s infrared sister, recently celebrated its 15th anniversary in space. Multiple X-ray observatories, including the Chandra X-ray Observatory, XMM-Newton, and the Nuclear Spectroscopic Telescope Array (or NuSTAR), also survey the sky from their high perches in space above the ground here on Earth. NASA has recently launched the James Webb Space Telescope, the next generation after Hubble and Spitzer, which will orbit the Sun.Putting a telescope in the earth’s orbit is not easy and comes with limitations. There are limitations on the size, for starters, as it acts as a payload on the rocket, and there’s not a lot of space to play with inside a rocket. Secondly, we have to keep in mind the reliability of the telescope as, god forbid, if something does go wrong with it, corrections and repairs are not that handy as compared to a telescope stationed on the surface of the earth; the main reason being the limited hands-on accessibility which we get with a telescope placed in outer space. These factors make space telescopes quite expensive, so why do we still place space telescopes?The James Webb Space TelescopeCredits: NASAPerforming observations from the Earth has a significant limitation of its own, mainly caused due to the atmosphere of our earth. Atmosphere causes filtering and distortion to the incoming electromagnetic radiation(light), also known as twinkling or scintillation. We do not have to worry about the distortion in the case of a space telescope as it is placed in outer space, receiving the incoming light before the earth’s atmosphere hinders or distorts it. Setting a space telescope also cancels out the effect of light pollution from artificial light sources present on the earth’s surface on the images captured by it. As a result, we get a final image with a higher angular resolution when compared to an earth-based telescope of a similar aperture.Picture by Hubble Space Telescope cropSrc: Wikimedia CommonsCurrently, there are seven classifications of telescopes that astronomers use. Each telescope uses a different method to scan the sky. X-ray, ultraviolet, optical, infrared, submillimeter telescopes, fresnel imagers, and finally, x-ray optics. Some of the powerful space telescopes launched to date are: Galileo’s telescope Isaac Newton’s telescope Hubble Space Telescope Solar and Heliospheric Observatory Arecibo Telescope Extremely Large Telescopes James Webb Space TelescopeWe will go through each of them in the upcoming articles in the series. So, come aboard on a stellar journey to explore the science behind telescopes!Further Reading Space Telescopes - Space Telescope Archive ESA - COROTREFERENCES Why Do We Put Telescopes in Space? - Scientific American Space Telescopes - Wikipedia Space Telescopes News – ScienceDaily Physics Central BBC Sky at Night MagazineHeader Image Credits: NASA" } , { "title": "Antimatter: Part I", "url": "http://blog.sedscelestia.org/Antimatter-Part-I/", "date": "October 1, 2021", "category": "Science", "tags": ["Observations","Skywatching"], "author": "Saieesh Sukhrani", "content": "Antimatter.What’s the first thing that comes to mind when we hear this term? A deadly bomb from Dan Brown’s “Angels and Demons”? Or some fictional term?Everyone knows antimatter is the opposite of matter, but how many understand the meaning of this?According to the Big Bang Theory, in the early universe, antimatter was created along with matter equally, but in our world, we don’t see antimatter at all, except when they are artificially created in our particle accelerators after much effort.Let’s start from the very beginning:Firstly, after Einstein published his Special Theory of Relativity, Victor Hess discovered cosmic rays (light belonging to celestial objects further away from us). Then the Quantum Theory was devised by Erwin Schrodinger and Werner Heinsberg.Later on, Paul Dirac wrote down an equation combining both Special Relativity and Quantum Theory, and just as \\(x^2 = 4\\) had two solutions, namely \\(+2, -2\\) so did Dirac’s equation. This suggests that if particles exist, so do “antiparticles”. If an electron exists, so must an “antielectron”, with the same mass but an opposite charge. Similarly for a proton, a neutron, nucleus, atoms, molecules, compounds and who knows maybe a whole universe. But, this was just a theoretical thought.This thought came to fruition when Carl Anderson discovered the “antielectron” or “positron” with the help of the cloud chamber. Soon, with the help of the proton accelerator, the “antiproton” and the “antineutron” were discovered.Further, Cronin and Fitch studied K-mesons (they studied a special type that was regarded to contain half of matter and the other half as antimatter) and found that they had different lifetimes, thus, it was noted that the fundamental symmetry principle of physics was violated.As stated above, scientists wanted to understand anti nuclei. Would it contain the symmetry similar to a nucleus (a neutron + a proton) as Dirac had predicted? The answer was found when the antideuteron was discovered at CERN. The nucleus of antideuteron found contained an antiproton and an antineutron (A deuteron nucleus consists of a proton and a neutron).With the help of Internal Storage Rings, the first proton-antiproton collision occurred and new discoveries, such as quarks and gluons (smaller parts of a proton) were identified.And, finally, in 1995, the first antiatom- antihydrogen was produced.The Atom and The AntiatomCredits: IndiaTodayTo test them further, scientists at CERN made antimatter ‘cold’ so they could study them before they could collide with matter. The mechanism of the same is shown below. They increased this time before it could collide to 16 minutes in 2011. In this time, antimatter was tested carefully with spectroscopy.The Cooling of Antihydrogen through LasersCredits: NatureLastly, the spectrum of matter and antimatter was compared when scientists began to observe a light spectrum originating from antihydrogen. The spectrum of both hydrogen and antihydrogen was similar. According to the Standard Model, both spectroscopic characteristics of matter and antimatter should be the same.Since, we know that matter and antimatter are not the exact opposites of each other; nature prefers matter over antimatter by 1 part in 10 billion, thus, scientists were curious to find the exact charge of antihydrogen. The result, based on 386 recorded events, gives a value of the antihydrogen electric charge as \\((-1.3±1.1±0.4) × 10-8\\), the plus or minus numbers representing statistical and systematic uncertainties on the measurement. This was found by studying the deflection of antihydrogen within an electric field. If it would deflect, then it wouldn’t be electrically neutral. And by how much it would deflect we could find out its value.With the help of the BASE (Baryon Antibaryonic Symmetry Experiment) , the magnetic moment of the antiproton was found to be \\(2.7928473441(42)\\). In the BASE, the team sets up two Penning traps – devices that hold particles in place with electromagnetic fields – the team aims to measure the antiproton magnetic moment to a hitherto unreachable part-per-billion precision.A direct measurement of the magnetic moment requires the measurements of two frequencies: the Larmor frequency, which characterizes the precession of the spin of a particle, and the cyclotron frequency, which describes a charged particle’s oscillation in a magnetic field.BASE’s double Penning trap separates the measurements of the Larmor as well as the cyclotron frequency from the spin-state analysis. Two traps are used for the measurements: the analysis trap, which will identify the spin state of the particle, and the precision trap, which will flip the spin of the particle while measuring the cyclotron frequency.Two further traps are used. The monitor trap will check for any variance in the magnetic field caused by external sources, allowing the BASE team to make instant adjustments to the core traps while measurements are underway. The reservoir trap will store antiprotons for months on end, allowing the BASE collaboration to continue operating even without a beam.The BASECredits: CERNThis ends the history for now, more research is ongoing on the same.When matter and antimatter collide, the only thing that remains is pure energy. The antimatter bomb as expressed in Angels and Demons is based on this.The Antimatter Bomb from Angels and DemonsCredits: The GuardianDuring the first fractions of a second of the Big Bang, the hot and dense universe was buzzing with particle-antiparticle pairs popping in and out of existence. If matter and antimatter are created and destroyed together, it seems the universe should contain nothing but leftover energy. But as mentioned above, nature favors matter over antimatter by 1 part per 10 billion, thus the whole universe is that tiny part that survived.Why?To find this out read the Part-2 of the Antimatter Series.Antimatter: once considered fictional, is now the rarest and the most dangerous and expensive “stuff” that can be produced. The cost of antimatter is about $62.5 trillion per gram.I hope you enjoyed part 1 of the antimatter series.In part two I will be including some of the theories suggested as to why there is a matter- antimatter asymmetry and the quantum entanglement of antimatter and matter.REFERENCES Antimatter - CERN Cost of Antimatter - NASA ScienceHeader Image Credits: CERN" } , { "title": "Space Tethers", "url": "http://blog.sedscelestia.org/Space-Tethers/", "date": "July 12, 2021", "category": "Science Space_News Space_Robotics", "tags": ["Science","Space_Tech","Space_Robotics","Technology_in_Space"], "author": "Suchetan R S", "content": "We as humans are pushing our limits in space exploration and are crossing the boundaries we never thought we would. But every time we blast off that 1.5 kilo-ton machine into space we incur huge costs. This limits our capabilities since the world runs on economic gain after all.Due to this huge requirement of energy, every rocket with the payload we try to put into orbit is nearly 90% fuel. The actual payload is just 4% of the total mass. 1Over the years, scientists have found many ingenious ways to overcome this barrier. One of the most ingenious solutions is the use of skyhooks or tethers!In layman’s terms, it is a sort of a rotating hook that is orbiting our planet. It is one of the most amazing applications of putting orbital energy to use.Figure 1: Momentum exchange tether in operation. 2Look at the illustration to get an intuitive idea about what tethers look like and how they function. In traditional rocket launches, the rocket is blasted off in order to reach the escape velocity of 11.2 km/s and escape the earth’s orbit. With a tether in place, things work a little differently. The bottom tip of the tether would be racing at about 4,000 km/hr through the uppermost layers of the atmosphere. We would have several opportunities to catch the bottom end of the tether. When the bottom end of the tether reaches the top most point, the task at hand would be to screw off from the tether and use the momentum to swing off and position ourselves into a higher orbit. Tethers can effectively reduce costs to position satellites into LEO (Low-earth orbit) by more than 50%.\\Figure 2: Tether tip approaching payload before attachment. 2A little more information about how a momentum-exchange tether (MXT) works: In simple words, the working is purely based on conservation of angular momentum. For example, as the tether passes through the perigee it’s COM would be moving at 8.9km/s with the tip velocity being 1.2 km/s. the orbital velocity of the payload must be ensured to be 7.7km/s. Since the motion of the tip of the tether and the spacecraft are opposite in nature, it ensures there is zero relative velocity between the center of mass of MXT and the payload just before the attachment which will lead to a successful catch of the payload. Once this is done, the MXT loses energy and assumes a lower orbit while the payload gains this energy. The payload gains the velocity equal to twice the velocity of its tip which in the illustrated case would be 2.4km/s which is the typical ΔV required for a GTO (Geosynchronous-transfer orbit) through perigee burn (Hoffman Transfer orbit).3 This gain is almost instantaneous and much faster than the conventional chemical propulsion. The figure illustrates this diagrammatically.This innovation, once mastered has countless applications. For example, an electrodynamic tether could be constructed. This 20 km long tether would be made of a conducting material which could produce 15-30 kW4 of power using the earth’s magnetic field (An effective application of Lorentz force). This could be used to power on-board experiments of many satellites.Tethers are not all easy to build, they have limitations as well. Objects in the low-earth orbit are subjected to noticeable erosion from atomic oxygen due to their high orbital speed with which the molecules strike. The space is filled with micrometeorites and space junk. Although these are being tracked on radar and have predictable orbits, a large piece could easily cut most tethers. Apart from these, there is radiation, including UV radiation which tend to degrade tethers and reduce its life span.There have been many successful space tether missions in the past including the SEDS-2 and the PMG missions 5. With technology advancing at a pace faster than ever before, there is nothing stopping us from building a successful MXT tether to lift off into space.References web.mit.edu - Rocket Principles ↩ web.wpi.edu - SPACE TETHERS: APPLICATIONS AND IMPLEMENTATIONS ↩ ↩2 wikipedia.org - Hohmann Transfer Orbit ↩ link.springer.com - Paper on A Brief Overview of Electrodynamic Tethers ↩ wikipedia.org - Space Tether Missions ↩ " } , { "title": "Roche Limit", "url": "http://blog.sedscelestia.org/Roche-Limit/", "date": "July 11, 2021", "category": "Observations Space_News", "tags": ["Observations","Roche_Limit","Skywatching"], "author": "Piyush Mohite", "content": "Ever wondered what would happen if our Moon gets too close to the Earth? When you try to imagine what happens when orbital planes, asteroids or satellites get too close to their primary gravity source (such as earth in our case), you may naturally imagine the two bodies drifting together and colliding, similar to what you see in the movies when an asteroid hits a planet. But instead what might happen, is that it will be torn apart before reaching the surface of the earth. Surprised? Let’s find out what really happens.What exactly may happen?It’s a little known effect for many new folk entering the world of astrophysics is what occurs when two (or more) orbital bodies find themselves in close proximity, cosmologically speaking, with a substantial mass difference. In case of very large bodies such as stars, you’d imagine them to be devoured by the larger gravity mass, entirely engulfed and consumed. In some cases, you’d be correct, depending on what speed and angle the smaller gravity object approaches. However, when there’s a gradual change or influence to orbital eccentricity, it’s entirely possible that the planetary object may reach and exceed their tidal or Roche Limit.About RocheThe Roche limit is named after French astronomy Édouard Roche, who published the first calculation of the theoretical limit, in 1848. Roche also left us with two other terms widely used in astronomy and astrophysics, Roche lobe (which is the region around a star in a binary system within which orbiting material is gravitationally bound to that star) and Roche sphere, both of which refer to the gravity in systems of two bodies.What is the Roche Limit?In celestial mechanics, the Roche limit, also called Roche radius, is the distance from a celestial body within which a second celestial body, held together only by its own force of gravity, will disintegrate because the first body’s tidal forces exceed the second body’s gravitational self-attraction. In simple words, it’s a distance, the minimum distance that a smaller object (such as our Moon) can exist, as a body held together by its self-gravity, as it orbits a more massive body (mainly its parent planet, such as the Earth in our case); closer in, and the smaller body is ripped to pieces by the tidal forces on it. In which case the result is the distortion leading to eventual destruction of the secondary body.Inside the Roche limit, orbiting material disperses and forms rings, whereas outside the limit material tends to coalesce. The Roche radius depends on the radius of the first body and on the ratio of the bodies’ densities.A large satellite (top) that moves well within a planet’s Roche limit (dashed curve) will be torn apart by the tidal force of the planet’s gravity. The side of the satellite closer to the planet feels a stronger gravitational pull than the side farther away, and this difference works against the self-gravitation that holds the body together. A small solid satellite (bottom) can resist tidal disruption because it has significant internal cohesion in addition to self-gravitation.Copyright 2010, Professor Kenneth R. Lang, Tufts UniversitySrc: Tufts UniversityHow does it happen?The Roche limit typically applies to a satellite‘s disintegrating due to tidal forces induced by its primary, the body around which it orbits. Parts of the satellite that are closer to the primary are attracted more strongly by gravity from the primary than parts that are farther away. And how the tidal forces come about? We know that gravity is an inverse-square-law force – twice as far away and the gravitational force is four times as weak, for example – so the gravitational force due to a planet, say, is greater on one of its moon’s near-side (the side facing the planet) than its far-side.Objects resting on the surface of such a satellite would be lifted away by tidal forces. A weaker satellite on the other hand, such as a comet, could be broken up easily when it passes within its Roche limit.ExamplesComet Shoemaker-Levy 9 was disintegrated by the tidal forces of Jupiter into a string of smaller bodies in 1992, before colliding with the planet in 1994.Src: http://hubblesite.org/newscenter/archive/releases/1994/26/image/c/Generally, no satellite can gravitationally merge out of smaller particles within the Roche Limit, since the tidal forces overwhelm the gravitational forces that normally hold the satellite together. Which is why, almost all planetary rings have been observed to be located within their Roche Limit. (Although some exceptions exist to this fact, notably Saturn’s E-Ring and Phoebe ring, which are predicted to be remnants from the planet’s accretion disk in it’s very early stages that failed to coalesce into small moonlets, or conversely have formed when a moon passed within it’s Roche radius and broke apart.)The best-known application of Roche’s theoretical work is on the formation of planetary rings. Since, within the Roche limit, tidal forces overwhelm the gravitational forces that might otherwise hold the satellite together, no satellite can gravitationally coalesce out of smaller particles within that limit. Indeed, almost all known planetary rings are located within their Roche limit. (Notable exceptions are Saturn’s E-Ring and Phoebe ring. These two rings could possibly be remnants from the planet’s proto-planetary accretion disc that failed to coalesce into moonlets, or conversely have formed when a moon passed within its Roche limit and broke apart.)Within our solar system, it is believed that Neptune’s moon, Triton — alongside Mars’ moon, Phobos will be the next witnessed casualties of the Roche Limit effect. The moons will eventually become ripped apart to form a ring around the planets. This is due to occur slightly outside of our timescale – predicted to occur from 10 million years’ time.Credits: Image Credit: NASA/JPL-CaltechTo tie this to something far closer to home – when the Sun turns into a Red Giant, our very own Moon is believed to be pulled out of orbit, closer to the Earth, to such an extent as to be torn apart, showering our planet with huge pieces of Moon debris (perhaps similar to the one that was created prior to the moon’s formation) as well as giving our planet a ring, albeit briefly (before the planet is destroyed by the red-giant). But then again, no need to worry, that’s very distant future.Determination\\Src: https://www.cs.mcgill.ca/~rwest/wikispeedia/wpcd/images/274/27408.pngGenerally the Roche radial distance largely depends on the rigidity and density of the satellite. Simply speaking, an ordinary star is much more easily ripped to piece by tidal forces – due to a supermassive black hole, say – than a ball of pure diamond (which is held together by the strength of the carbon-carbon bonds, in addition to its self-gravity). On one hand, a completely rigid satellite will maintain its shape until tidal forces break it apart. Whereas, a highly fluid satellite gradually deforms leading to increased tidal forces, causing the satellite to elongate, further compounding the tidal forces and causing it to break apart more readily.Roche radius is typically quantified as being 2.5x the radius of the primary gravity source:\\[Radius_{Primary} \\approx 2.5 * Radius_{Planet}\\]More accurately, taking into account the densities of both the satellite and the primary body, the Roche limit distance is given by the following equation:Where \\({R_M}\\), is the radius of the primary, \\(ρ_M\\) is the density of the primary, and \\(ρ_m\\) is the density of the satellite.I’ll leave out the derivation of the above formula for the reader to read in the sources down, since it’s somewhat beyond the scope of this article although not very difficult if you’re familiar with the Newton’s law of Gravitation and comfy with a tad bit of math.The formula for fluid satellites, which is a more accurate approach for calculating the Roche limit is again, slightly complicated, so I’ll be leaving that part as well. But the reader can access it through the links in the references.Some selected examples:And there you have it, I hope you had fun reading about a trivial yet interesting celestial phenomenon. If you’re more interested, you can check out the following stories: Astronoo’s article on Roche limit Phobos Might Only Have 10 Million Years to Live Ancient Solar Systems Found Around Dead Stars Observing an Evaporating Extrasolar Planet Check out these Astronomy Cast episodes for more on Roche limits: Tidal Forces, Tidal Forces Across the Universe, and Stellar Roche Limits A nice little visualization by LynnREFERENCES Universe Today Futurism WikipediaHeader Image Credits: NASA/JPL-Caltech" } , { "title": "Astrophotography For Beginners", "url": "http://blog.sedscelestia.org/Astrophotography-for-Beginners/", "date": "March 8, 2021", "category": "Uncategorized", "tags": ["Observations","Astrophotgraphy","Beginner","Skywatching","Camera"], "author": "Shriram Joshi", "content": "The night sky can be considered as one of the most magnificent spectacles that we can experience every night. The twinkling stars, the bright moon and the cold yet exciting breeze all make the experience of stargazing literally out of the world. However nowadays as many of us live in populated cities where it is almost impossible to escape the light pollution it is very difficult to view the night sky at its complete beauty. In such cases devices like the DSLRs or even smart phones can come to our rescue.Credit/Copyright: Keith Quattrocchi of Lost Valley ObservatoryAstrophotography is one of the most interesting, yet a very unpopular hobby one can take up. In this article we will help you get started with the basics of how to spot and photograph night sky objects using nothing but your mobile phones. Most smartphones come with Camera applications that have a “pro” mode that lets you control most of the parameters of a photograph. If not, there are apps available on the app stores that let you do the same. Along with a Camera app that has a “pro” mode one might also need a night sky map application. These apps help you locate stars, constellations, and planets. Once you have these apps ready it is time to dive into the basics of photography. The three pillars of photography are the ISO, aperture and shutter speed/exposure time. We will go through these briefly one by one. You can find the formal definitions of these online however in this article we will discuss how these different parameters affect your image.The ISO in simple terms is a setting that determines the brightness of the image. More the ISO, the brighter your images will be. You can understand ISO as the measure of sensitivity of your camera towards light. Most phone cameras give a range of ISO from 100 to 1600/3200. The standard ISO range for daylight images is 100-800, however, to photograph the night sky a higher ISO number is required. Generally, for night sky images you can set the ISO to 1600 or above. However, there are a few downsides to this. If there is a lot of light pollution around you, higher ISO may induce some noise in your image.Src: Wikimedia CommonsThe next parameter is the aperture. Aperture is the opening of your camera lens. It basically means that increasing the aperture increases the amount of light as well as the focal length. Changing the aperture changes the depth of your image. The aperture generally has a notation like f/6.3 and is also called the f number. If the f number is larger the aperture is larger resulting in a blurred background and low depth of field. On the other hand, a small f number means a greater depth of field and the background is less blurred. With respect to astrophotography a small f number is preferred. The objects being photographed can be considered at infinity and thus are hard to be focused on. Thus, there is no single focus point, and it is thus desirable to not blur the parts of the image that are not in focus (i.e. the background).Src: Wikimedia CommonsThe third pillar of photography is the shutter speed. As the name suggests it’s the time for which your shutter opens to expose the sensor. Shutter speed is measured in seconds or minutes. If measured in seconds it is denoted as a fraction. For example, 1/240 means 240th of a second or 5’’ means 5 seconds. For astrophotography we generally deal with exposure times ranging from 1 to 30 seconds. Long exposure shots sometimes lead to long trails of stars that arise due to shakes. It is thus important to find the right support or holder for your phone or camera to reduce these shakes.Src: Wikimedia CommonsSome of the key things to follow while doing astrophotography include, ensuring that there is no light directly falling on your camera. This will create a lot of noise in your pictures. It is good to find a spot where there is minimum light from any sort of light sources. A terrace is an ideal spot. Another thing to look out for is using a good support for your camera. Tripods do the job better. In some cases, to reduce the shake from your own hand it is handy to use 5 or 10 second timers. This gives your tripod or support some time to dampen the shake from your button press. You can experiment with all sorts of settings to find out the best combination for the conditions you are shooting in. It always helps to take some time before starting to get your settings adjusted. For more information you can always go through the material and videos available online.Header Image Credits: Photo by Usukhbayar Gankhuyag on Unsplash" } , { "title": "Messier 45: Pleiades", "url": "http://blog.sedscelestia.org/Messier-45-Pleiades/", "date": "February 8, 2021", "category": "Uncategorized", "tags": ["Messier-Series","Pleiades","Star_Cluster"], "author": "Ashutosh Gupta", "content": "The Pleiades star cluster is also known as the Seven Sisters or M45. It is visible from virtually every part of the globe. We can see it from as far north as the North Pole, and farther south than the southernmost tip of South America. It looks like a tiny misty dipper of stars. They are a group of more than 800 stars located about 410 light-years from Earth in the constellation Taurus, the Bull.It is an example of an open star cluster, a group of stars born around the same time from a gigantic cloud of gas and dust. The brightest stars in the formation glow a hot blue and formed within the last 100 million years. With life spans of just a few hundred million years, they are incredibly luminous and will burn out rapidly, far less than the billions of years our sun will enjoy.Credits: NASA, ESA, AURA/Caltech, Palomar ObservatoryThe star cluster takes its English name from the legends of Greece. The Pleiades are the seven daughters of Atlas, the Titan king, and Pleione, the ocean nymph. Atlas revolted against Zeus, the king of the gods, during an ancient battle, who then sentenced his opponent to keep the heavens forever on his shoulders. The sisters were so sad that Zeus allowed them a place in the sky to be close to their father.HistoryThe first astronomer to view the Pleiades through a telescope was Galileo Galilei. He thus found that many stars in the cluster are too faint to be seen with the naked eye. In March 1610, in his treatise Sidereus Nuncius, he published his observations, including a sketch of the Pleiades showing 36 stars.Galileo’s drawings of the PleiadesCredits: History of Science Collections, University of Oklahoma LibrariesIn 1767, John Michell determined that the likelihood of a chance alignment of so many bright stars was just 1 in 500,000, so it surmised that the Pleiades and many other star clusters must be physically related. When studies were first made of the stars’ proper motions, it was found that they are all moving in the same direction across the sky, at the same rate, further demonstrating that they were related.Charles Messier measured the cluster’s position and included it as M45 in his catalogue of comet-like objects, published in 1771.CompositionMessier 45 contains several hot, blue, extremely luminous B-type stars and is one of the nearest star clusters to Earth. It has a core radius of 8 light-years, and its tidal radius extends to about 43 light-years. The cluster is home to more than 1,000 confirmed members, but only a handful of these stars are visible to the naked eye. The total mass of M45 is estimated at 800 solar masses.The cluster contains many brown dwarfs, which are objects with less than about 8% of the Sun’s mass, not heavy enough for nuclear fusion reactions to start in their cores and become proper stars. They may constitute up to 25% of the cluster’s total population, although they contribute less than 2% of the total mass. Astronomers have made great efforts to find and analyse brown dwarfs in the Pleiades and other young clusters because they are still relatively bright and observable. In contrast, brown dwarfs in older clusters have faded and are much more challenging to study.How to LocateThe Pleiades cluster is straightforward to find. It is located about 14 degrees northwest of Aldebaran, the brightest star in Taurus and 14th brightest star in the night sky. When the cluster is high in the sky, it can be located by following the line formed by the three bright stars that form Orion’s Belt: Alnilam, Alnitak and Mintaka. M45 lies to the northwest of the celestial Hunter.Special CharacteristicsCredits: StarryNightThe nine brightest stars of the Pleiades are named for the Seven Sisters of Greek mythology: Sterope, Merope, Electra, Maia, Taygeta, Celaeno, and Alcyone, along with their parents Atlas and Pleione. By pointing Kepler at the Pleiades, researchers confirmed that six of the Seven Sisters — Alcyone, Atlas, Electra, Merope, Taygete and Pleione — are slowly pulsating type B stars, which change in brightness over the course of one day. The seventh star, named Maia, has a brightness that fluctuates over a more extended period of 10 days." } , { "title": "Messier 97: Owl Nebula", "url": "http://blog.sedscelestia.org/Messier-97-Owl-Nebula/", "date": "January 25, 2021", "category": "Uncategorized", "tags": ["Observations","Owl_Nebula","Messier-Series"], "author": "Gayatri", "content": "The Owl Nebula, also known as Messier 97 (M97), is a planetary nebula located in Ursa Major. The nebula lies at an approximate distance of 2,030 light years from Earth. It is known for its distinctive shape, resembling a pair of owl-like eyes, that can be seen in larger telescopes. Learn more about it in this interesting article by our club member Gayatri.IntroductionJust below the bowl of the Big Dipper in the constellation Ursa Major, lies the celestial body Messier 97, commonly known as the Owl Nebula. It is a planetary nebula named for the two dark regions within it giving it the appearance of an owl’s head with large eyes.Credit/copyright: Keith Quattrocchi of Lost Valley ObservatoryThe Owl Nebula is located around 2030 light years away from Earth, with an apparent magnitude of +9.9. It can be viewed in its full glory through a telescope with an aperture of 10 inches or more, during spring in the northern hemisphere. It has a spatial diameter of about 1.82 light years and is around 8000 years old.HistoryThis nebula was discovered by the French astronomer Pierre Méchain on February 16, 1781, noting that it was faint and difficult to see. Soon after, Charles Messier observed the nebula and added it to his catalogue as M97. In 1837, Admiral William Henry Smyth first classified it as a planetary nebula. Lord Rosse first sketched the nebula with a resemblance to an owl in 1848, causing it to be named as such. He noted the presence of sparkling stars with dark penumbra around spiral arrangements, calling the nebula resolvable.Original drawing of the Owl NebulaCompositionThe Owl Nebula is believed to have formed during the death of a G-type main sequence star, as it collapsed from a red giant to a white dwarf, ejecting material into the surrounding interstellar medium. It is composed of around 0.13 solar masses of matter, including the elements oxygen, hydrogen, helium, sulphur, and nitrogen. Its structure consists of 3 concentric shells arranged around the white dwarf star, the innermost of which is barrel shaped. The outflow of jets of stellar wind from the central star along with this is likely the cause for the special owl-like appearance of the nebula.Special CharacteristicsThe nebula lies 2.5 degrees southeast of Merak, which is the star at one of the corners of the Big Dipper’s bowl. It has been found to be much brighter visually than photographically, emitting much of its light in a green spectral line. It is one of only 4 planetary nebulae in Messier’s catalogue of celestial bodies, and is designated as NGC 3587 in the New General Catalogue. The Owl Nebula bears a striking likeness to another planetary nebula in the constellation Hydra, known as the Southern Owl Nebula.Southern Owl Nebula as captured by ESO" } , { "title": "Eagle Nebula", "url": "http://blog.sedscelestia.org/Eagle-Nebula/", "date": "December 2, 2020", "category": "Uncategorized", "tags": ["Observations","Nebula","Pillars_of_Creation","Messier-Series"], "author": "Afraj Shaikh", "content": "SEDS Celestia presents to you this amazing article about one of the most beautiful nebula present in this universe, Eagle Nebula. This articles talks in depth about interesting facts, science and history of this nebula including “The Pillars of Creation”. Dive right in to learn all about it .Three-color composite mosaic image of the Eagle Nebula, with north at top.Credit: ESONebulas are one of the most fascinating astronomical objects and have been a keen interest of astronomers for centuries. One of the most popular among them is Eagle Nebula. Eagle Nebula, also known as the Star Queen nebula is located in Serpens constellation at Serpens Cauda (the tail of the constellation). This nebula has been given sixteenth place in the Messier catalogue and has been blowing astronomers’ mind with its stellar beauty.HistoryEagle Nebula or M16 was discovered by Jean-Philippe de Cheseaux in 1745-46. It is a part of IC 4703, the H II region, a type of emission nebula located in the Sagittarius arm of the Milky Way Galaxy. In late 18th century, when this object began to be catalogued by astronomers, only the star cluster was visible and it was assigned as M16, which later came to be known as Snow Queen cluster.Later, further studies revealed that there is a large area of glowing hydrogen which covers the star cluster and is invisible to the naked eye. It somewhat resembled as an eagle stretching its wings, which gave rise to its common name. As there was more advancement in astrophotography, we began to explore various features of the nebula especially dark nebula (dark patches in the above image) and many features were also given special name which we would be discussing in the next section!!Pillars of Creation“The Pillars of Creation” – NASA, ESA and The Hubble Heritage TeamIn 1995, Eagle Nebula grabbed the world’s attention when two astronomers, Jeff Hester and Paul Scowen used Hubble Telescope for capturing a large region of stellar formation inside the nebula which later became popular as the “Pillars of Creation”. The dark patches in the picture were believed to be protostars. These columns are composed of materials which are essential for the formation of stars like interstellar hydrogen and dust, and stretch to about 4 light years in space. Astronomers have also discovered dense pockets of Evaporating Gaseous Globules (EGGs) on the surface as well as inside these columns. Most of the EGGs lack enough gases needed for star formation but some of these will eventually lead to the formation of new stars. The name “Star Queen Nebula” was introduced by American astronomer Robert Burnham Jr. as its central pillar resembled to the Star Queen shown in silhouette.In recent years, few observations have made astronomers question the existence of the Pillars of Creation. In 2007, an evidence from Spitzer Telescope suggested that the Pillars of Creation may have been destroyed due to shock waves generated by a supernova explosion which had occurred some 8000-9000 years ago and the light has already gone past us but due to the slow-moving shock waves it will take more thousand years to observe the destruction of the Pillars. Similarly, in 2010 NASA’s Chandra Observatory’s images showed that there were only a handful of X-Ray sources (randomly generated dots) and they do not coincide with the pillars, since new stars are considered to be a hotbed of X-ray sources, this led scientists conclude that the star formation days of Pillars of Creation are over and the Pillars have already been destroyed. But, in 2014, the pillars were imaged by Hubble telescope for the second time and this time giving more accurate information on the rate of evaporation occurring within the pillars. Scientist later discovered that no supernova explosion had occurred inside the pillars and the pillars are estimated to last at least for another 100,000 years.Stellar SpireStellar Spire in the Eagle Nebula, Image: NASA, ESA and Hubble Heritage TeamStellar Spire is another active region of star formation located to the left of Pillars of Creation. It is a large tower of gas and is approximately 90 trillion kilometers in length. The ultraviolet light coming out of the young stars inside the spire have eroded it and is responsible for illuminating the rough surface of the spire.CompositionThe Eagle Nebula occupies an area of 70 by 55 light years in size (30 arc minutes) while its open star cluster has radius of about 15 light years (7 arc minutes in diameter). The brightest star in the Eagle Nebula is HD 168076. It is a binary star system which consist of O3.5V and O7.5V stars. This binary star system has an apparent magnitude of 8.24 and can be observed with good binoculars. This star has mass roughly 80 solar masses and luminosity of up to 1 million times of that of the Sun.The young open star cluster associated with Eagle Nebula; NGC 6611 was formed 5.5 million years ago. It is a type-c cluster which means it is very loose and irregular. The ultraviolet glow of hot, blue stars of this cluster is mainly responsible for the brightness of Eagle Nebula. Scientists suspect that the nebula has various such type of star-forming clusters within it.LocationM16 is about 7000 light years away from earth and resides in Serpens constellation. Its co-ordinates in Equatorial Co-ordinate system is given by RA 18h 18m 48s Dec -13° 49’ 0’’. M16 has an apparent magnitude of 6. There are different stars and constellations near M16 which also helps in providing its relative position with respect to them.For example, it is located 2.5 degrees in west of Gamma Scuti and a few degrees north of Omega Nebula. It can also be located using Teapot, a famous asterism located in Sagittarius constellation. First, find the brightest star in the Teapot (Kaus Australis) and then follow a line from Kaus Australis to just east of Kaus Media. During clear sky, finding the star cluster of M16 is very easy but for viewing its surrounding one must require a telescope with a large aperture.Here comes the end of this article, I guess I have covered a lot of interesting facts about Eagle Nebula. So, let me summarize some of the facts: –Eagle Nebula – Messier 16Constellation: Serpens (at Serpens Cauda)Coordinates: Right Ascension 18h18m48s, Declination -13°49′0’’Distance: 7,000 light yearsVisual magnitude: +6Absolute magnitude: -8.21Apparent dimensions: 30 arc minutesRadius: 70×55 light yearsEstimated age: 5.5 million yearsDesignations: Eagle Nebula, Star Queen Nebula, Messier 16 (M16), NGC 6611, IC 4703, Gum 83, Sharpless 49, RCW 165I hope this article would have given a brief insight about the Eagle Nebula. Well, Eagle Nebula is just one of the many fascinating messier objects and there’re lots of them to come in this messier series so do keep a track of them!!" } , { "title": "Messier 44", "url": "http://blog.sedscelestia.org/Messier-44/", "date": "November 9, 2020", "category": "Uncategorized", "tags": ["Star_Cluster","Observations","Messier-Series","NGC-2632"], "author": "Abdul Jawad Khan", "content": "Messier 44, or NGC 2632 is more commonly known as Praesepe or the Beehive Cluster. It is an open star cluster in the constellation Cancer, and is one of the nearest open clusters to Earth. An open star cluster is basically just a group of stars formed from the same giant molecular cloud, and thus have roughly the same age. M44 is a cluster of more than 1000 stars . Messier 44 has experienced mass segregation, a process often seen in star clusters and other gravitationally bound systems (e.g. galaxy clusters), by which heavier objects move toward the center, while lighter ones move away from the center. The bright, massive stars of M44 are now concentrated in the central region of the cluster while the fainter, less massive members are found in the halo.Beehive Cluster. Atlas Image obtained as part of the Two Micron All Sky Survey (2MASS)M44 has an apparent magnitude of 3.7, and can easily be seen without binoculars. It appears as a blurry patch of light to the naked eye. However, the cluster is best seen with binoculars and small telescopes. The brightest stars in M44 have a visual magnitude of 6 to 6.5 and appear blue-white in color.HistoryWilhelm Schur’s map of the Beehive Cluster in 1894Messier 44 is a prominent deep sky object and has been known since ancient times. Classical astronomer Ptolemy described it as “nebulous mass in the breast of Cancer”, and it was among the first objects that Galileo studied with his telescope, even being able to resolve about 40 stars. Charles Messier added it to his famous catalog in 1769 after precisely measuring its position in the sky. Along with the Orion Nebula and the Pleiades cluster, Messier’s inclusion of the Beehive has been noted as curious, as most of Messier’s objects were much fainter and more easily confused with comets.CompositionAltogether, the cluster contains at least 1000 gravitationally bound stars, for a total mass of about 500–600 Solar masses. A recent survey counts 1010 high-probability members, of which 68% are M dwarfs, 30% are Sun-like stars. Also present are five giant stars and eleven white dwarfs. Due to mass segregation, the brighter and more massive stars are closer to the core of the cluster while the smaller ones are towards the periphery.M44 is estimated to be about 600 million years old, and has been measured to be at an estimated distance of 182 parsecs.Special CharacteristicsIn 2012, scientists discovered two planets orbiting two separate stars in the Beehive Cluster. These were the first planets discovered orbiting Sun-like stars in a star cluster. The planets, designated Pr0201b and Pr0211b, are hot Jupiters, extra-solar gas giants with characteristics similar to Jupiter and high surface temperatures because they have a much closer orbit to their parent stars. These planets are also known as roaster planets, epistellar jovians or pegasids.Praesepe, Asellus Australis and Asellus Borealis.Image: WikiskyM44 also occupies a special place in Greek and Roman mythology. Greek and Roman observers saw the cluster as a manger from which two donkeys are eating. The donkeys, represented by the nearby stars Asellus Borealis and Asellus Australis (Gamma and Delta Cancri), were the mythical animals on which the god Dionysus and his companion Silenus rode into battle against the Titans. In the myth, the Titans were frightened by the donkeys’ braying, which helped the gods win the battle. The donkeys were placed in the sky as a reward, along with the Manger, or Phatne in Greek." } , { "title": "M51: Whirlpool and Co.", "url": "http://blog.sedscelestia.org/M51-Whirlpool-and-Co/", "date": "October 26, 2020", "category": "Uncategorized", "tags": ["Observations","Whirpool_galaxy","Spiral_galaxy","Messier-Series"], "author": "Aeishna Khaund", "content": "The Whirlpool galaxy is a beautiful spiral galaxy, tagged as “grand-design” due to its prominent and well-defined spiral arms. This bright, easy-to-locate spot is part of the Canes Venatici constellation.Credits: NASA, ESA, S. Beckwith (STScI) and the Hubble Heritage Team (STScI/AURA)However, the words ‘Messier 51’ can denote a whole collection of night sky objects, apart from this galaxy.While M51 generally denotes the Whirlpool Galaxy, its smaller, interacting sidekick galaxy also goes by the same Messier tag. To differentiate between the two, the following convention was adopted.Messier 51a : Whirlpool Galaxy (NGC 5194)Messier 51b : NGC 5195But that’s not all. The ‘Messier 51 Group’ refers to an entire group of galaxies. All within the Canes Venatici, it even includes another Messier object! Apart from the companion 51b, the Sunflower galaxy (M63) is a noted member of the group. M51a is the titular member and brightest of this 7 member group.HistoryWhen Messier added the 51st object(s) to his list, he labelled it as a nebula within the Milky Way! This misconception, starting in 1773 with Messier himself, carried on well into the 20th century. In fact, even its little galaxy friend was discovered 8 years later by Pierre Méchain. At that time, it wasn’t clear whether these galaxies were simply passing by each other at a distance or actually interacting.In 1845, William Parsons, the 3rd Earl of Rosse, examined this little spot a bit closer and realized that it was spiral in nature. It now came to be known as Rosse’s Question Mark and placed in the collection of known ‘spiral nebulae’.Rosse’s accurate depiction of the M51 pair.It was finally in 1929 that Edwin Hubble’s publication declared that all of the apparent ‘spiral nebulae’ are actually distant spiral galaxies. Soon, Radio Astronomy made it clear that the companion NGC 5195 galaxy was, in fact, interacting with the Whirlpool and all the misconceptions were cleared.CharacteristicsThe galaxy is 43% the size of our Milky Way and 10.3% the mass. It is roughly 23 million light years away and has a dust-occluded blackhole at its center. As the top picture shows, the red light is an indicator of hydrogen in inetense star-forming regions, blue is an indicator of young stars and yellow shows matured stars.It seems that the Whirlpool owes a lot to its companion. This small galaxy, trying to glide past M51a, has intersected with the Whirlpool multiple times, giving it its beautiful arms. The star factories in the arms are aided by the NGC 5195’s tidal force. The center of the galaxy is a region of especially enhanced star formation.This wonderful duo and their surrounding galaxies share an interesting history and are surely worth an amateur astronomer’s time to try and observe in the night sky." } , { "title": "M104 Sombrero Galaxy", "url": "http://blog.sedscelestia.org/M104-Sombrero-Galaxy/", "date": "October 12, 2020", "category": "Uncategorized", "tags": ["Messier_Series","Skywatching","Sombrero_Galaxy"], "author": "Bhuvan S V", "content": "IntroductionWhen we hear the word “galaxy”, perhaps one of the most imagined pictures is that of the M104, or commonly called Sombrero Galaxy. With its flat, disc shape and being surrounded by white light coming from its stars, it is one of the most iconic images ever taken by the Hubble Space Telescope.The Sombrero Galaxy is a giant elliptical galaxy about 31.1 million light years away from the Milky Way. It is 49,000 light years wide, and has a bright nucleus (with a supermassive black hole), a large central bulge, and a dust lane surrounding it, giving it the appearance of a sombrero hat, hence the name. it also has an apparent magnitude of +8.0, and is also considered by some to have the highest absolute magnitude for a galaxy 10 Megaparsecs from Milky Way.HistoryIt was discovered by a French astronomer Pierre Méchain on May 11, 1781. William Herschel also discovered it independently in 1784, also noting the presence of a “dark stratum” (now the dust lane). Camille Flammarion included it in the Messier Catalogue after finding Messier’s personal list of Messier objects in 1921, which also included the Sombrero Galaxy. Since then, it has been known as M104.Pierre MéchainCompositionOne of its most prominent features is its dust lane, a symmetrical ring that encloses the bulge. It consists of most of the cold atomic hydrogen gas and dust. The nucleus consists of weakly ionized gases, but its source is still uncertain, with answers varying from hot, young stars to its active galactic nuclei. No significant star formation is seen in the nucleus, hence the most probable answer is the active galactic nuclei with its supermassive black hole (with a minimum mass of 10^9M_☉).It also has a relatively large number of globular clusters, about 1,200 to 2,000.Neighborhood and how to find itSombrero Galaxy lies in cloud of galaxies south of Virgo cluster, 11.5 degrees west of Spica and 5.5 degrees east of eta Corvi. But it is unknown if it is a part of the group of clouds itself. Some methods suggest it is in a group that also includes galaxies such as NGC 4487, NGC 4504, and others. While other methods suggest it is not a part of any group at all. It is accompanied by an ultracompact dwarf galaxy, discovered in 2009, which has an absolute magnitude of -12.3 and a radius of just 47.9 light years.With its large bulge, beautiful dust lane, and almost perfectly elliptical shape, it never ceases to amaze amateur and professional astronomers alike." } , { "title": "Messier 3", "url": "http://blog.sedscelestia.org/Messier-3/", "date": "October 5, 2020", "category": "Messier_Series Observations", "tags": ["Messier_Objects","Messier_Series","Observations","Science","Skywatching","Telescopes"], "author": "Abdul Jawad Khan", "content": "Messier M3 is a globular cluster of stars in the constellation Canes Venatici, the Hunting Dogs. Messier 3 is one of the brightest, largest globular clusters in the sky, and is famous for its unusually large variable star population. It has an apparent magnitude of 6.2 and is approximately 33,900 light-years distant from Earth. It has the designation NGC 5272 in the New General Catalogue. It was the first Messier object to be discovered by Charles Messier himself, who originally mistook it for a nebula without stars.Messier 3 is one of the most popular targets among amateur astronomers. M3 has an apparent magnitude of 6.2, making it difficult (but not impossible) to see it without binoculars even in good viewing conditions. However, the cluster appears fully defined in a moderately sized telescope. A 4-inch telescope will reveal the bright core without resolving individual stars, whereas a 6-inch instrument will resolve some of the outer stars. The central region of M3 can only be resolved into stars by larger instruments, starting with telescopes with a 12-inch aperture.HistoryM3 was discovered on May 3, 1764, and was the first Messier object to be observed by Charles Messier himself, although he took it to be a starless nebula. This was corrected after the stars residing in the cluster were resolved by William Herschel around 1784. Since then, it has become one of the best-studied globular clusters, owing to its huge variable star population.Lemuel Francis Abbott, Public domain, via Wikimedia CommonsWilliam Herschel (by Lemuel Francis Abbott, painting, 1785)CompositionM3 is one of the largest and brightest star clusters there are, being made up of around 500,000 stars. It is estimated to be 11.4 billion years old and is located at a distance of 33,900 light-years from earth.It contains mostly old, red stars, a large number of variable stars, and a number of blue stragglers – blue main-sequence stars that appear to be young and are bluer and more luminous than other stars in the cluster. These stars are now believed to form as a result of stellar interactions.Special CharacteristicsAs already mentioned, M3 has a very large number of variable stars. Variable stars are different from normal stars in that their brightness fluctuates with time. For some variable stars, their period relates to their intrinsic luminosity, so astronomers can use those stars’ brightness fluctuations to estimate their distances. This makes them extremely useful for measuring distances to deep-sky objects. Hnce the Me3 globular cluster is a very interesting place for astronomers to study, with new variable stars being discovered even to this day. Currently, there are about 274 known variable stars found in M3.M3 is a fascinating object, and is one of the most notable ones as well, allowing astronomers to further discover more objects in our sky and study them using the variable stars found in M3.Credits: NASA, ESA, STScI and A. Sarajedini (University of Florida)M3, as seen by Hubble Space TelescopeHeader Image Credits: Adam Block/Mount Lemmon SkyCenter/University of Arizona" } , { "title": "Introduction To Messier Objects", "url": "http://blog.sedscelestia.org/Introduction-to-Messier-Objects/", "date": "September 28, 2020", "category": "Messier_Series Observations", "tags": ["Clusters","Comets","Introduction","Messier_Objects","Messier_Series","Observations","Series","Skywatching","Stars"], "author": "Kaustubh Murudkar", "content": "Hello everyone! This article is the first in the Messier object series of articles which will be conducted by SEDS Celestia! In this article, I’ll be going over what exactly the Messier Objects are and what makes them really significant. In the later articles we will be having a look at different interesting Messier Objects in detail. So sit tight, relax and have a good read!So when did this exactly start?Charles Messier was born on 26 June 1730 in Lorraine, France. At the age of 14 he saw the “great comet” (try guessing what that is XP) appear in the skies above Lorraine and 4 years later he also saw the annular solar eclipse of 1748. Perhaps these were the events which started his lifelong love for astronomyDuring those times, finding out a comet made an astronomer quite popular among his/her peers. And you even got to name that comet! On his quest to find a comet, Messier realized that there were many objects that could be mistaken to be comets, but were stationary. He felt the need to document these objects so that they will not be mistaken by him (or others) as comets. Thus, began the Messier catalogue with its first entry being the Crab Nebula (M1) in 1758.Crab nebulaCredits: NASA, ESA, J. Hester and A. Loll (Arizona State University)Fun Fact- Messier actually found out a couple of genuine comets when he was trying to catalogue non-cometary objectsAnsiaux (1729—1786), Public domain, via Wikimedia CommonsDoesn’t he look a bit goofy XD?Messier Objects : Our Deep Sky Companions…Now, Lets talk a bit about the Messier Objects themselves. As David Levy writes in the foreword to The Messier Objects, “There can be no better exercise for a beginning astronomer than to find and observe all of the Messier objects”. There are 110 of them, consisting of star clusters, nebulae and galaxies. Most of them are found by Messier himself but some were found by other astronomers too.So by now, many of you readers might have a question that- Yo this stuff is cool and all, But what made these catalogue of objects so popular that we are using it almost 250 years from its inception?Allow me to explain, dear reader. You see, what Messier wanted was to create a list of “nuisances” while searching for comets. Turns out these nuisances were in fact some of the brightest objects in the night sky! Such a list was never made before, and when it was, we kinda stuck to it! Having a list of deep sky objects to watch was a boon to the amateur astronomers. Any person with a decent telescope can watch these objects in the clear night sky with sufficient clarity. And the experience of watching something quite literally “out of this world” was pretty damn exciting!Credits: Mike Keith, 2014The Messier catalogue is so popular that there are even periodic tables of it xPWhat can you expect from the later articles in this series?In the next articles in this series, we will be going through some of the most popular Messier Objects. Along with an in-depth information about them, we will also be including their location in the night sky and ideal viewing conditions as well.I hope this introductory article made you readers excited of what’s about to come!Src: MonSFFA Astronomical CartoonsAww, that caveman didn’t know about Messier objects!Header Image Credits: NASA, ESA, the Hubble Heritage Team (STScI/AURA) and R. Gendler (for the Hubble Heritage Team); Acknowledgment: J. GaBany" } , { "title": "Perplexing Paradoxes", "url": "http://blog.sedscelestia.org/Perplexing-Paradoxes/", "date": "August 10, 2020", "category": "Science", "tags": ["Maths","Paradox"], "author": "Neil Shah", "content": "How many Paradoxes can you find?Let’s break down the word paradox to find out what it means. “Para” comes from Latin meaning “distinct from” and “Dox” comes from Doxa meaning “our opinion”. So paradox literally translates to “distinct from our opinion”. But, that doesn’t help much, does it? People often think paradoxes as unsolvable brain teasers, but they’re so much more than that. So what exactly is a Paradox?In 1962 W.V.Quine classified paradoxes into 3 major categories:ANTINOMYParadoxes that reach self contradictory results by applying generally accepted ways of reasoning. For e.g. the famous Penrose Triangle is a visual antinomy. Some other visual antinomies are shown below.Other examples include the famous sentence we all have thought of in our childhood: “this sentence is false.” The sentence is self contradictory if we just go along what the sentence means, i.e. if the sentence is false then it means that the sentence must be true; but if the sentence is true then it was never false in the first place and hence the self contradiction. As Quine put it, they create a “…crisis in thought”.FALSIDICALIs it possible to mathematically prove that 1=2? - QuoraA falsidical paradox establishes a result that not only appears false but actually is false, due to a fallacy in the demonstration. The various mathematical proofs (such as 1=2) are classic examples of this, often relying on a hidden division by zero. Most of Zeno’s Paradoxes are Falsidical in nature. It is described by Quine as one that “….packs a surprise, but is seen as a false alarm when we solve the underlying fallacy.”\\(1 = 1\\)\\(1 - 1 = 1^2 - 1^2\\)\\(1 - 1 = (1+1)(1-1)\\)\\(\\frac{\\cancel{(1-1)}}{\\cancel{(1-1)}} = \\frac{(1+1)\\cancel{(1-1)}}{\\cancel{(1-1)}}\\)\\(1 = 2\\)VERIDICALA Veridical paradox often produces absurd and counter-intuitive results that are further proved to be true. The famous Monty Hall problem is an example of Veridical paradox (discussed further). As described by Quine, “…packs a surprise, but the surprise quickly dissipates itself as we ponder over the proof”.\\[*\\]That’s enough with the definitions. Let’s now go ahead and look at some perplexing paradoxes. (Disclaimer: this article doesn’t discuss Time Travel Paradoxes as they deserve an article of their own.)Moore’s ParadoxStatement : I know it is raining. But I do not believe it is raining.Statement : I know Coronavirus has been affecting people all over the world. But I do not believe Coronavirus exists.The paradox arises in the absurdity of the statement that you know something (p) but do not believe in p. The first author to note this apparent absurdity was G. E. Moore. These ‘Moorean’ sentences, as they have become known, are paradoxical in that while they appear absurd, they nevertheless Can be true; Are (logically) consistent; and Are not (obviously) contradictions.One of the more interesting Moorean logics is that we as humans know that all humans have at least some amount of inconsistencies in their opinions and beliefs. This means we know there must be a few fallacies in the opinions we have. Yet we believe all our opinions to be true.Moore’s paradox is an example of antinomy in logic.\\[*\\]Achilles’ ParadoxLet’s say, there is a race between a Tortoise (T) and Achilles (A). T is given a headstart of some distance. Now the race begins, and A runs quickly towards T, but by the time A reaches the initial position of T, T itself has moved by some distance forward. Now A tries to catch up with T again, yet again by the time he reaches T’s position, T has moved some distance forward. Now the whole process works all over and over again infinitely and yet T is ahead of A. Inductively, we see that no matter how much A tries T will always be ahead of him and A can never overtake T. This completely absurd as even I can overtake a tortoise and I’m no Achilles!Resolution:Achilles paradox is one of Zeno’s paradoxes of motion in 5th Century BCE. The argument of Achilles never being able to overtake is not wrong but rather incomplete. Let’s see how we can prove the argument wrong. Let’s say Achilles’ speed is 1 unit/s and Tortoise’ speed is 0.5 unit/s and there is a distance of 1 unit in between them. By the First iteration A moves 1 unit (to initial position of T; meanwhile T has moved 0.5 units), by second iteration A moves 0.5 units (to the second position of T; meanwhile T has moved 0.25 units) and so on…Simply calculating the Distance Achilles moves: S = 1 + 0.5 + 0.25 + 0.125 …..We all know that this summation converges to S = 2 units and since A’s speed is constant (1 unit/s), time taken by him to cover this distance = 2 seconds.We can verify this resultInitial distance between A and T = 1 unitRelative speed of A with respect to T = (1 – 0.5) unit/s = 0.5 unit/sTime taken for A to catch up to T = Distance/ Rel. Speed = 1/0.5 = 2 secondsWhich is the same as we got from above.This is a very surprising result as calculating S from the above equation requires the use of modern mathematics. This means proving this paradox took about 2000 years! This paradox is an example of Falsidical Paradox since the reasoning does not take into consideration that infinite series may be convergent and give a finite value. For about 2000 years Achilles paradox was thought to be an Antinomy. This just goes to say that some paradoxes which we may think are antimonies may be proven to be Falsidical by using some even more advanced tools.Now every time you overtake something while moving, remember there were infinitely many steps/ divisions between you and that object before you actually overtook it.🙂\\[*\\]Ship Of TheseusTheseus was thinking one day when I replace one of the planks on my ship, it still remains my ship. Let me replace another plank, well it is still my ship. Now if I keep doing this and one by one all the original pieces are replaced by a new piece, is this still my ship? Furthermore if I use the old pieces and place them perfectly in the same position as they were originally, which one truly is my ship?Resolution: There are many theories on the resolution of this Paradox, but the most compelling one is the “gradual loss of identity over time”. As the parts of the ship are replaced, the identity of the ship gradually changes. At any given instance, instead of saying that it is still the same ship, it would be more accurate to say it is a “replica” of the original ship. As the parts are replaced, the new boat becomes exactly that; a new boat. This theory suggests that the ship made from the original parts in the same position as before will be the original ship, as those parts are the actual pieces that participated in Theseus’ journeys. A constantly changing identity begs the question of “Who am I”?Amazing consequence of this resolution is that You are not the same You from 7 years ago. As all of the cells that make up your body get renewed completely in around 7 years. So the person you look at in your old photos is not You but a replica of You from 7 years ago.\\[*\\]Drinker’s ParadoxStatement: At a club, there always exists a particular person such that if he is a drinker, then everyone else present at the club is a drinker.Resolution: the apparently paradoxical nature of the statement comes from the way it is naturally stated. It seems counterintuitive that there could be a person who is causing others to drink. To prove this statement let me first explain what “vacuously true” statements are.Vacuously true statements are statements which are true only because the antecedent cannot be satisfied.For eg, “All bottles in this room are red”, will be true even if there are no bottles in that room because there is no antecedent of any bottle of any colour other than red present in that room.Another example would be “If Eiffel tower is in London, then Delhi is the capital of Russia”. Since the first “if” part of the statement is false, no other information can be drawn from the second “then” part of the statement. This is a characteristic consequence of vacuous truths that no real information can be gathered from that statement.So to explain our apparent paradox we split the statement into two conditions,First, where everyone at the club is a drinker. Hence we may choose any person and this statement holds.Second, where one or more than one at the club is not a drinker. If we choose one of the non-drinkers, then the first part of the statement is not satisfied (that if a particular person drinks…), hence the following part of the statement holds no truth value and hence is a true statement. We could have even said “if a non drinker drinks, then earth is flat”. This would still be logically true as the statement forms a vacuous truth.This Paradox is a Veridical Paradox as it is simply a play with words and after a bit of explanation the truth emerges within the statement itself.Amazing Consequence of this is every time you find yourself alone in the room; remember that you are the smartest, loveliest, best looking and healthiest person in that room.😉\\[¯\\backslash\\_(ツ)\\_/¯\\]\\[*\\]Some Paradoxes to ponder uponBarber’s ParadoxStatement: Does a barber who only shaves those who do not shave themselves, shave himself?Interesting number paradoxStatement : There can never exist an uninteresting number (out of all infinite numbers). Since if there existed a list of uninteresting numbers then there would be a number which would be the smallest uninteresting number, which itself makes it interesting.Unexpected Test ParadoxStatement: A teacher announces there will be a Surprise test in the next week’s weekdays. The students think that the test can simply not occur on Friday because if it did not happen by Thursday the students will know it will be on Friday and it wont be a surprise. Hence the test cannot happen on Friday. By similar argument the test cannot happen on Thursday, and inductively on none of the days of the upcoming week. The students relax thinking there will be no test but the teacher takes a test on Wednesday anyway, taking everyone by surprise! Where was the fallacy in the logic of the students?Staircase paradoxA stair has height of 3 and width 4. So an ant crawling from the bottom to the top will have to cover a distance of 7. Now the stair is divided into two stairs of height 1.5 and width 2 each. Still the ant has to cover a distance of 7. Keep repeating the process of dividing the stairs into smaller and smaller stairs. Now suddenly we see something like a hypotenuse of a triangle. And by Pythagorus’ theorem we get that the length of that hypotenuse is 5. So herein lies the paradox, does the ant walk 5 units or 7 units? Or is 5=7?!Pythagorean “Paradox” (right-angled triangle). - Mathematics Stack …(Spoiler alert: while you are thinking about this, also think about fractals 😉)Expired poisonStatement: Is an expired poison more poisonous or is it harmless?Gabriel’s HornGabriel’s horn is a mathematical object with finite volume but infinite surface area. This in simple terms means that if we try to paint the inside of the horn, you will always run out of paint, but if we pour the paint into the horn, it will fill the horn using a finite volume of paint.vsauce theme plays in the background.Buridan’s AssStatement: A donkey is kept exactly between two identical stacks of hay. The Hay are of identical size, shape and emit identical odour (basically the same in all aspects). How will the donkey ever choose which hay to go for first? Will it simply starve itself to death because there are two perfectly identical foods available for it and it cannot decide?Omnipotent GodCan an Omnipotent (one who is capable of doing everything – an all powerful being) God create an object that it cannot lift?\\[*\\]Well if you have stuck around till the end, I heartily thank you for reading. ❤Paradoxes provide an amazing and unique way of thinking. It is the passion of thought that drives us to think the unthinkable.“This, then is the ultimate Paradox: To Discover something that thought itself cannot think.”–Søren Kierkegaard" } , { "title": "Dummy's Guide To Celestia Observations", "url": "http://blog.sedscelestia.org/Dummy's-Guide-to-Celestia-Observations/", "date": "August 3, 2020", "category": "Uncategorized", "tags": ["Lasers","Observations","Sky","Skywatching","Telescopes"], "author": "Aeishna Khaund", "content": "If you are in the habit of taking a leisurely stroll past the Cricket Grounds after dinner, you know that sometimes, vague shapes can be seen moving around at the center of the grounds, in pitch darkness. If you ever stop to take a better look, you will also see green flashes of laser, pointing deep into the sky. And if you are reasonably well informed, you know that this is a Night Sky Observation by Celestia, in process.If you have seen posters for this event, and are curious about what goes on in these observations, then this article is a fun introduction and guide for you. In short, you can guess the basic process from the name: we get telescopes to the Ground and practice what is called, Observational Astronomy. But if you actually happen to be at one, this is what a session generally involves:Level 1: BeginnersThe easiest thing to locate, observe and most importantly, feel awe at, is the Moon. So naturally, that will generally be the first thing you observe through the telescopes in your first session. It takes special filters to observe the moon, since it is too bright to view without decreasing the light intensity. While you wait for your turn at the telescope, the green lasers are pointing out the famous constellations and stars in the sky; the ones you have probably heard of before. While Observation Team members are probably already explaining handy tricks to be able to locate them, there’s a cheat code: Star Trackers. Since this is likely to be the coolest takeaway from your first observation session, you can find out more for yourself at the cricket grounds (Celestia even has an in-house version if you are interested). Now you can go ahead and pretend to be a star geek in front of friends.Level 2: Regular Attendees8 inches DobsonianIf you think observations become boring after the novelty of the first few sessions wears off, you might want to take a peek at what you are missing out on. The bustling crowd from the first observations of the year now thins out, leaving the cricket grounds more peaceful for observations. Once you are a familiar face here, you might be allowed to tinker around and actually try using the telescopes by yourself. While the beautiful white Dobsonians are simple to understand, definitely don’t touch the more conventional-looking Celestrino without supervision (try finding out more about why the word ‘balancing’ strikes fear among the best of us). With enough interest, you now know how to locate the more prominent constellations and have heard the buzzword, ‘Messier Objects’, being thrown around a lot. Bonus: you can now boss around not-so-regular attendees for not following the Commandments of the Grounds (see the section named thusly).The Commandments of the GroundsWhile you are here, take note of these precautions that every attendee must adhere to. No flashlight within a 5-meter radius of the observation spot. No pointing lasers into hostel rooms and at airplanes, tempting as it might be. Shielding the mouth of the telescopes from any bright light, such as lasers, phone screens, or flashlights. Level 3: Loyal AttendanceYou have achieved this level of expertise if you now despise the Moon and know the distasteful nickname for Orion’s sword. And if you really belong here, you have heard the Lore of the Black Dobsonian. While we make no promises, on a certain dark night of the year, you might be summoned to the assembly of this monster. Keep your fingers crossed.Bonus Levels: “Stars aren’t my thing.”Even if you are simply unable to get the hang of astronomy, there are still great incentives for you to attend Observations. Suit yourself:For the PhotographerIf you are up for a challenge, Astrophotography is a whole new set of techniques and equipment to master. You can find many astrophotography enthusiasts at the grounds on any observation night. And if you decided to give this addictive pastime a try, do consider contributing to Celestia’s existing repository of starry pictures.Milky Way Galaxy as clicked by our Astrophotography expert Yashraj PatilFor the Bonfire enthusiastNo, we do not hold bonfires on the cricket pitch. But we often sit in cozy circles on the ground to gossip, listen to ‘life gyaan’ from seniors and explain the mythology behind the constellations. If some of these mythologies sound made-up, it is because they very often are. If you are good at making up stories, join the party. If you are already used to doing these things, might as well do them under a starry sky at 3:00 am, as far away from the lights as you can get, on campusFor the Spotify Playlist enthusiastYes, Bluetooth speakers are a regular. Come over and fight for control over the music and then contemplate life with appropriate background music.In ConclusionCome to the Observations. They may be more interesting than you imagine.Header Image Credits: Photo by Phil Botha on UnsplashBlog Image Credits: SEDS Celestia" } , { "title": "Understanding Telescopes and Binoculars - Part3", "url": "http://blog.sedscelestia.org/Telescopes-and-Binoculars-Part-3/", "date": "July 27, 2020", "category": "Uncategorized", "tags": ["Skywatching","Telescopes","Optical_aid","Observations","Coordinate_system"], "author": "Avdhoot Bhandare", "content": "Co-ordinate SystemsHey guys, it’s me again, your friendly backyard telescope-man! You must be really persistent (read stubborn) if you haven’t given up yet, which is good, cause you need your wits about you if you want to survive through this article. So if you’re not Albert Einstein’s great great grandson or something, you might as well leave.Naw, man, I’m just kidding, you don’t need to be that smart to understand celestial co-ordinate systems. Even if you’re his great great nephew twice removed, we’ll make it work (sorry, I’ll stop). Anyway, that’s why I’m here for, right, to help you grasp this fundamental and very important part of telescopes and amateur astronomy. So without further jokes, lets get into it!Since you’ve read the first two articles (I hope), you know what binoculars and telescopes are, and you have a rough idea of how they work. You must also have noticed that I skipped explaining what mounts are. That was because, to understand mounts, you need to understand the directions of the sky. Similar to how you would direct a person to the nearest post office, “take a left here, go straight for a couple of minutes, another right, and you’re there,” you also need directions for the sky right? But it’s kinda complicated when you try that with the stars. I mean, how do you tell someone where a star exactly is in the sky?Equatorial Co-ordinate systemCredits: The SAO Encyclopedia of AstronomyTurns out, there are many ways to do that, but we’ll stick to the two most common methods. First, imagine the co-ordinate system. Grid lines on the earths surface. Next, think of a big, clear glass globe surrounding the earth, through which you can see the entire sky, each and every star and cluster, everything. With me so far? Now, take your grid lines, and just expand them outwards till they sit on the clear glass globe. What do you see now? You see little squares in the sky, exactly like the ones you see on a map of the earth! Just like that, you’ve portioned the entire, messy night sky into neat little cubes.This method is called the equatorial co-ordinate system, and is very widely used, because it is standard, easy to understand, and is independent of the location of the viewer. The “longitude” is called the Right Ascension (or RA for short), and similar to how the prime meridian is in Greenwich (wherever that is), RA is measured in hours, minutes and seconds from the line where the ecliptic intersects the celestial equator (which is basically the point at which the sun is during the Vernal Equinox). The “latitude” or Declination (lazy people call it Dec) simply measures how much to the north or south a particular object is from the celestial equator. Simply put, the pole star is 90 North (almost) and the equator is 0.Now, this might be a little too much to take in, so I request you to read it through slowly, a couple of times until you’ve got it down in your head. If the vernal equinox thingy goes over your head, don’t worry, it sometimes skips over mine too, and it’s not really that important when you’re using the co-ordinates.Why is this so widely used and important, sensei, you may ask. Well, for several reasons. First, it’s based on the co-ordinate system, which everyone knows how to use (I hope) and is comfortable with. Secondly, it’s as standard as can be. A star will have the same co-ordinates, if you observe it from India or Australia or the middle of the Pacific Ocean (well actually it changes with the earths orientation over a period of 26,000 years, but I don’t think it will bother us too much, with our puny 80-90 year lifespans). It is also independent of time, meaning that the co-ordinates are the same at any given time. To make it simpler to understand, our grid-lined glass orb is fixed in space, and doesn’t rotate with us. But since we’re so narcissistic, the glass sphere rotates around us, as in the earth (16th century Church has entered the chat). This perspective will help to understand the next system, but more on that later. Basically the RA/Dec system helps people all over the world, in different times and locations confer and discuss without any confusion. It does have it’s own difficulties though. Wrapping your head around it takes time, and it’s kind of inconvenient when you want to quickly set up an observation, since you need to do a bit of calculation according to your location. Well worth the effort, though.There are many, many little intricacies that one needs to understand about this system, but it’s impossible to tell them all here. I quite strongly suggest that you go and watch a couple YouTube videos to understand how exactly this system works, and you’ll understand it much better.Detailed RA/Dec SystemAnyway, moving on to the second system. You may remember that I was saying that it’s stupid and narcissistic to want to be the center of the universe (well I might not actually have said that, but I mentioned the 16th century Church, so all that goes without saying). So, umm, now say that you’re such a self centered prick (just say it, I’m not saying you are one, you know. Probably). Okay, so are you in that frame of mind? Great. Now, take the glass, grid lined globe we had in the first system, and instead of centering it around the Earth, center it around yourself. That’s it, basically. Your horizon is now the “equator” of this globe, and the “prime meridian” is the North South line. Pretty easy, huh?The Horizontal Coordinate SystemCredits: Time and Date ASThis system, called the horizontal, topocentric, or Alt-Az system (Altitude-Azimuth System), is much simpler and convenient to use. The angle that an object makes in the sky with the horizon is called the Altitude of the object. The “latitude” of this globe, if you will. Secondly, the Azimuth is the “longitude” of this object measured from the North-South circle on this sphere. Now that we got that out of the way, let’s focus on the peculiarities of this system.First off, you may have realized that half the sphere is inside the Earth. Well, actually not half, a tiny whit less than that because of the earths curvature, but for once let’s assume that your location on the earth is a flat plane (Flat earth society has entered the chat. Sigh). This fact doesn’t really concern us, because all we care about is the half above, right? Secondly, an important fact to understand is that this system is in the viewers frame of reference, that is, it makes it as convenient as possible for the viewer. It stays put, as the night sky rotates around us. As you might imagine, the co-ordinates of each object in the sky changes with time, and hence it will be quite difficult (read impossible) for two people to collaborate with this system. Also, the co-ordinates will vary with each and every location on the earth, and it is very dependent on an app or website from which you can find out the exact co-ordinates for an object at your exact location and time.Putting these problems aside, it is a really wonderful and user friendly co-ordinate system. Once you’ve found the co-ordinates of a particular object, it is child’s play pointing your Dobsonian mounted telescope (we’ll get to that later) at the object. Even if you don’t have a telescope, it’s easy to understand that 64/43 means 64 degrees above the horizon and 43 degrees to the east of north.Again, goes without saying, please go through this a few times more, look it up on the internet, just make sure you’ve got it down before moving on to the mounts. If you understand these systems, you’ll have a much better understanding of how the two types of mounts work, which we’ll go over in the next article.Well there you have it, the two most commonly used co-ordinate systems for the night sky. Both of them have their specialties, both of them are wonderful and unique in their own stead, and we really need a good understanding of these systems if we want to be a good amateur astronomer. We’ll have a look at telescope mounts in the next article, and till then, happy stargazing!" } , { "title": "Our Universe In The Infrared Spectrum", "url": "http://blog.sedscelestia.org/Our-Universe-in-the-Infrared-Spectrum/", "date": "July 13, 2020", "category": "EM_Cosmology Science", "tags": ["Astrophysics","Cosmology","Electromagnetic_radiation","EM_Astronomy","EM_Cosmology","Infrared","Observations"], "author": "Abdul Jawad Khan", "content": "When we look up at the night sky, we see thousands of bright specks of lights, pointing towards stars and nebulae and galaxies, but beyond those shiny dots, lie hundreds of thousands of planets, moons, and dust clouds. They aren’t visible to our eyes since they do not emit any visible light, and since they aren’t actively emitting energy through various processes like nuclear fusion, our radio telescopes aren’t able to detect them either. So how do we study these outliers? How do we image them, and discover and probe into their existence? The answer lies in something which every security guard is doing nowadays before letting us enter somewhere – infrared imaging, or in our case, infrared astronomy. We already know that visible light is but a small portion of the electromagnetic spectrum, and there is a lot which we can’t see. Infrared refers to the portion of the electromagnetic spectrum that begins just beyond the red portion of the visible region and extends to radio waves at longer wavelengths, having wavelengths between 0.75 to 300 micrometers. What makes infrared radiation so special is that it is a result of an object possessing heat energy. Anything that has a temperature above absolute zero radiates in the infrared. Even we humansradiate most strongly in the infrared at a wavelength of about 10 microns. Even ‘night vision’ goggles make use of the infrared radiation being emitted by objects to essentially ‘see’ in the dark, and that is the same thing we do when searching for planets in the darkness of space.Src: DK Find OutAn example of IR imaging of a childThe Birth of Infrared AstronomyThe earliest account of someone observing infrared radiation goes back to 1800, where William Herschel performed an experiment where he placed a thermometer in sunlight of different colors after passing it through a prism. He found that the highest temperature was found outside the visible spectrum, just beyond the red color. He dubbed this radiation “calorific rays”, and went on to show that it could be reflected, transmitted, and absorbed just like visible light.Then, in 1856, astronomer Charles Piazzi Smith detected infrared radiation from the Moon, while doing mountain top astronomy.The Advent of Modern Infrared AstronomyEarlier, the field of infrared astronomy didn’t take off, since there were many hurdles in the way. One of the biggest ones is out atmosphere, which has gases like water vapor and carbon dioxide which absorb infrared radiation, especially the faint signals coming from distant sources. Thus, infrared astronomy for objects farther than our solar system is basically impossible on low ground, and astronomers have to mount their infrared telescopes on planes and weather balloons to make meaningful observations.The atmosphere absorbs a huge portion of electromagnetic spectrumAnother major hurdle in detecting infrared radiation is the instruments themselves.Imagine trying to take a photograph with a camera that was glowing brightly, both inside and out. The film would be exposed by the camera’s own light, long before you ever got a chance to take a picture! Infrared astronomers face the same problem when they try to detect heat from space. At room temperature, their telescopes and instruments are shining brilliantly in the infrared. In order to record faint infrared radiation from space, astronomers must cool their science instruments to very cold temperatures. Thus, they have to place their instruments in space and cool them using liquid helium.The Spitzer Space TelescopeDusty Galaxies and Star FormationOne might think that the vastness of space between the stars in a galaxy is just empty, however, it is filled with something we call the interstellar medium – composed of gas atoms and molecules, in addition to solid dust particles. Although it is a near-vacuum, with only a few hundred dust grains per cubic kilometer, on galactic scales, the effect of the gas and dust is visible. These dust grains absorb and reflect the ambient ultraviolet and optical light produced by the stars, producing a dimming and reddening effect, and radiating it in the far-infrared regions. This makes the galaxies appear dimmer than they are, and in actuality galaxies are twice as bright as they appear to be.NGC 4414 is a beautiful example of a spiral galaxy.Credit: NASA/JPL-CaltechThere is a huge amount of space dust between the stars of a galaxyThe interstellar medium is a reservoir from which matter for new stars can be drawn. Molecular clouds are dense regions within the interstellar medium where the concentrations of gas and dust are thousands of times greater than elsewhere. These clouds are often hiding stellar nurseries, where hundreds of stars are being formed from the dense material. Because these newborn stars are swaddled in dense cocoons of gas and dust, they are often obscured from view. The clearest way of detecting young suns still embedded in their clouds is to observe in the near-infrared. Although visible light is blocked, heat from the stars can pierce the dark, murky clouds and give us a picture of how stars are born. Some scientists are even convinced that we may be able to find elements essential to life in these dust clouds, and that the origins of life may lie in those regions.Studying PlanetsSince planets do not emit any noticeable radiation of their own, they cannot be detected easily with conventional methods like telescopes and astronomers have to resort to indirect means caused by the slight gravitational tugging of planets on their local suns or by the slight apparent dimming of the star’s light as a large planet passed “in front” of it. However, with the use of infrared astronomy, these planets can be seen and even characterized by the infrared radiation they emit.With the advent of the Spitzer Space Telescope, astronomers have also observed protoplanetary disks around stars – leftover debris from the formation of a planetary system, providing evidence that other solar systems may be common. Actually, an “excess” of infrared light seems to radiate from the region around all types of stars, so, planets may not only be common, but they may also be around every type of star in the universe!Credit: NASA/JPL-Caltech/UCSCThis series of temperature maps made using Spitzer Space Telescope data depicts wild temperature swings as extrasolar gas planet HD 80606b travels in a highly elliptical orbit around it’s star. Bright areas are hottest.Although stars are comparatively much hotter, and therefore emit much more infrared radiation than the planets around them, it is much easier to differentiate the infrared radiation coming from a planet and a nearby star that it is to find the same difference in other regions of the electromagnetic spectrum. The Spitzer Space Telescope has the sensitivity and stability to detect the infrared radiation from extrasolar planets directly. Spitzer has seen it from extrasolar planets; identified water and other molecules in the atmospheres of exoplanets; and characterized the “weather” in terms of wind speeds and rates of heating and cooling.Finding OutliersLarge-scale surveys, like the 2MASS (Two-Micron All-Sky Survey), conducted in the infrared region, has helped identify outliers like Brown Dwarfs – failed stars, and Red Quasars. These objects are different in the fact that they emit very little radiation of their own, and most of the visible light they emit is redshifted to infrared wavelengths. Thus, they are hard to detect without the help of infrared telescopes like the Spitzer. Studying these objects helps develop our understanding of the universe.Credit: NASA/JPL-Caltech/UCSCA Brown Dwarf - a failed star which is more like a very large planet. It can fuse Deuterium but cannot sustain long term nuclear fusion.An artist impression of a red QuasarFrom its murky beginnings in the 19th century, and its period of neglect in the early 20th century, infrared astronomy has become a valuable field of study, helping us uncover the mysteries of the universe, aiding our search for life on extraterrestrial planets, and even pointing us towards answers concerning the origins of life itself. When we start looking beyond just what our eyes can see, we start to truly understand how vast and unexplored our universe is!Header Image Credits: NASA/JPL-Caltech" } , { "title": "A Brief Overview Of R P Feynman's Thesis", "url": "http://blog.sedscelestia.org/A-Brief-Overview-of-R-P-Feynman's-Thesis/", "date": "July 6, 2020", "category": "Science", "tags": ["Astrophysics","Physics","RP_Feyman","Science"], "author": "Bhuvan S V", "content": "IntroductionRichard Feynman is one of the most famous physicists of the 20th century, changing our notion of a typical scientist (the uncombed, white hair, a big mustache, donning a white coat, can be attributed largely to Einstein). While we know him as the prank-loving, bongo-playing, safe-cracking, and feminizing genius, most of us forget about his contributions to physics, especially the field of Quantum Chromodynamics (or QCD), for which he won the 1965 Nobel Prize in Physics, along with Julian Schwinger and Schin’ichiro Tomonaga.Two of his works are well known. The first, now known as Feynman diagrams, simplified large equations to easily understandable diagrams, which has made the works of many particle physicists easier. The second, the path integral formulation, was, and still is, a very important tool in quantum mechanics. In this article, we shall see the origins of the path integrals, in his 1942 PhD Thesis.MotivationConsider a free charged particle accelerating in space. As any accelerated charge would, this particle would emit radiation, thereby losing energy (law of conservation of energy). This loss of energy is simply explained in case of a charged particle in a potential field; say an electron in an atom- the potential of the positively charged nucleus would do the work necessary to decrease the energy of the electron. But for a free charge, there is no such potential to do the needed work.The then accepted explanation was that the charged particle would act on itself- the work is done due to “self-energy”. Feynman wished to remove this self-energy, by introducing another charge particle, which would act on the radiating particle. This can be possible when one sees that Maxwell’s equations allow for two solutions- one with positive time and other with negative time. The mechanism is as follows: the radiation from particle 1 would cause particle 2 to emit radiation back to particle 1, thereby affecting it. This seemingly violates principle of causality, but when you consider a large number of particles and both solutions of Maxwell’s equations, this is seen to actually obey it. Feynman calls this theory, which he developed along with his advisor John Archibald Wheeler, the theory of action at a distance (now called Wheeler-Feynman absorber theory). The main principles of this theory are as follows: Acceleration of a charged particle is due to its sum interactions with other charged particles, or, there is no “self-energy”. This also means that a free particle alone cannot spontaneously emit radiation. The force due to the charged particles is the Lorentz force, or, there is no underlying field in free space. The fundamental phenomena in nature are symmetrical with respect to past and future. This means, the solutions to Maxwell’s equations are sum of half the retarded (positive time) solution and half the advanced (negative time) solution. Since this theory is difficult to represent in Hamiltonian formulation (it isn’t possible to express as harmonic oscillators, as there are other interactions as well), we use the principle of least action from classical mechanics to find the equations of motion. We also note that the Wheeler-Feynman theory is now considered to be not true.I. Least action in classical mechanicsThe first part of the thesis deals with the principle of least action in classical mechanics. To go further we need to be familiar with some terms and results that shall be used throughout the thesis: Functional: A functional analogy" } , { "title": "International Space Station: Is it really worth it?", "url": "http://blog.sedscelestia.org/ISS/", "date": "June 29, 2020", "category": "Uncategorized", "tags": ["ISS","Rockets","Space_Robotics"], "author": "Ashutosh Gupta", "content": "“I think both the space shuttle program and the International Space Station program have not really lived up to their expectations.”-Buzz AldrinThe International Space Station (ISS) has been such a significant accomplishment in human space history, and it has contributed a lot to our understanding of space. It flies 400 km high at speeds that defy gravity. It only takes the weightless laboratory 90 minutes to make a full Earth circuit at 28,800 km/h. It is the result of unparalleled cooperation in engineering and science between five space programs representing 15 countries. The five participating space agencies are NASA (United States), Roscosmos (Russia), JAXA (Japan), ESA (Europe), and CSA (Canada). The space station is about 109 by 73 meters: a permanently crewed 460-ton platform. Recently the station made news relating to two significant events. On 30 May 2020, SpaceX’s Dragon spacecraft soared in the air over Cape Canaveral, Florida, aboard Falcon 9. As the capsule docked the following day with the International Space Station, Robert Behnken and Douglas Hurley made history as the first astronauts on a commercial craft to ride into orbit. On 10 June 2020, a team of NASA scientists created the fifth state of matter, the Bose-Einstein Condensates (BEC)-the existence of which was predicted by Albert Einstein and Indian mathematician Satyendra Nath Bose almost a century ago. Due to the microgravity of the station, the BECs lasted more than a second which offered the team an unprecedented opportunity to study their properties. Many scientists and experts claim ISS is the beginning of the human race’s in-depth space exploration and colonization.The BeginningThe station’s story began on 25 January 1984 when President Ronald W. Reagan addressed his state of the Union and directed NASA to develop a “permanently crewed space station and to do it within a decade.” NASA laid out an ambitious space station plan consisting of three separate orbital platforms to perform microgravity research, Earth and celestial observations. Also to serve as transport and servicing node for space vehicles and satellites and as a staging base for deep-space explorations.Participating NationsRepresentatives from the USA, Russia, Japan, Canada and participating countries of the ESA met at the US State Department in Washington DC on 29 January 1998. They signed an Inter-Governmental Agreement on their cooperation for the construction and utilization of the space station.Ten months later the Russians launched the Zarya module from the Baikonur Cosmodrome in Kazakhstan, the first feature of the on-orbit portion of the ISS. The first American part, the Unity Node 1 module, arrived three weeks later on the Space Shuttle Endeavour, beginning to construct the most extensive international space platform. In July 2000 the Zvezda Service Module followed, providing crew members with living quarters. On 2 November 2000, the first crew to occupy the station’s orbital facilities were the Expedition 1 Commander William M. Shepherd, Flight Engineer and Soyuz Commander Yuri P. Gidzenko, and Flight Engineer Sergei K. Krikalev.The End of the BeginningMore than 40 assembly flights were required to build the entire station. By 2020, 36 space shuttle flights had delivered elements to ISS. Other assembly flights included modules Falcon 9 lifted, the Russian Proton rocket or the Soyuz-U rocket, in the case of Pirs and Poisk. Now the ISS has become a massive artificial object in space, and the largest satellite in low Earth orbit, visible frequently to the naked eye from the surface. The station is split into two main sections: the Russian Orbital Segment (ROS), which is operated by Russia; and the US Orbital Segment (USOS), which other nations share.Initially, the ISS was planned to last until 2015, just after the Space Shuttle program had stopped. Still, Congressional hearings extended its lifespan until 2024, with ISS partners discussing a possible extension until 2028. Several significant new Russian elements for ISS are scheduled for launch starting in 2020. These include modules like European Robotic Arm, Nauka, Prichal and some more.Nauka ModuleThe present options for ISS post-2028 are privatization: the 2019 budget of President Trump follows the first step, which aims at a budget blackout by 2024. Gaining private investment successfully in the ISS would require the reform of the National Lab on the ISS. Or the station could be deorbited, or recycled for future space stations in orbit.The CriticismIn 1990 The American Physical Society reviewed the experiments then planned for ISS. Much of the research included looking at materials and fluid dynamics in the microgravity environment of the station. Other proposed tests focused on the station cultivating protein crystals and cell cultures. However, Physical society decided that such experiments would not provide sufficient useful scientific knowledge to justify the station’s construction.The station has since been revamped, and the list of planned experiments has improved, but the research community remains staunchly opposed. To date, at least 20 research organizations from around the world have concluded that the tests on the space station are a waste of time and resources. Some of these organizations include the National Science Foundation (NSF), American Chemical Society, Institute of Electrical and Electronics Engineers (IEEE).These scientists have distinct reasons to disapprove of the station. It is too unstable a platform for researchers in the material sciences. The vibrations make it difficult for astronomers to observe the heavens and for geologists and climatologists to study the Earth’s surface as well as they could with remotely operated satellites. The cloud of gases vented from the station interferes with the experiments that require close-vacuum conditions. And lastly, the station orbits only 400 km overhead, passing through an already extensively explored area of space.People often regard the International Space Station as the budget hemorrhaging laboratory orbiting Earth, as it has become one of NASA’s most expensive projects. To date, more than $87 billion has been poured into the station, according to NASA’s Inspector General (IG), and it is projected to spend between $3 billion to $4 billion a year to sustain the station. In total, maintaining the ISS includes a fifth of NASA’s $19.1 billion budget and even the path to deorbit the station would cost $950 million and will take three years. The total cost of the project is approximately at $150 billion of which NASA supports 76.6%, with Japan second at 12.8%, European partners at 8.3% and Canada finishing up the last 2.3%.The Major ContributionAlpha Magnetic Spectrometer-02In response to some of these criticisms, crewed space exploration supporters argue that critique of the ISS mission is short-sighted, and that it has created measurable benefits worth billions of dollars for people on Earth. For example, studies on bone density loss in space have helped patients with osteoporosis on Earth. The Alpha Magnetic Spectrometer-02 collected particles which suggest the existence of dark matter but do not prove it. Crystal growth experiments are helping researchers on Earth understand the structure and functions of proteins. Trials in blood work and respiration have helped to look for innovations in fighting chronic illnesses such as cancer and asthma.The ConclusionSome advocates argue that apart from its scientific value, it is an essential example of international cooperation, and it is an asset that could allow more economical Lunar and Mars crew missions.While others believe it is a black hole that absorbs funds and is far from achieving any significant scientific output.So whether the ISS program has justified the efforts of many nations that went behind it and the taxpayer’s money still remains highly debatable.*The views in the article are solely of the author and does not represent the views of the club or the blog management" } , { "title": "Solar Eclipse 101", "url": "http://blog.sedscelestia.org/Solar-Eclipse-101/", "date": "June 22, 2020", "category": "Uncategorized", "tags": ["Annular","Earth","Moon","Mythology","Penumbra","Sun"], "author": "Kaustubh Murudkar", "content": "“If this could be repeated every day for a year, I would never budge from where I stood”-Wendy MassSolar Eclipses are a sight to behold. They are often called ‘the nature’s greatest coincidences’ and continue to fascinate people from all around the world. So, in this article, lets get to know everything there is to know about Solar eclipses.Solar eclipse on June 21 as captured by our member Aryan NigamA bit about the history…Humans have documented solar eclipses for millennia. References to them can be found in humanity’s earliest texts, such as the ancient Chinese academic documents. In China, solar eclipses were thought to be associated with health and prosperity of the emperor, and failure to predict one will put the emperor’s life in danger. Legend has it that 2 astronomers Hsi and Ho, were executed for not predicting the solar eclipse which occurred on 2 October 2134BC, making it one of the earliest known sightings of a Solar Eclipse.Debate even swirls around a line from Homer’s Odyssey — ”The sun has been obliterated from the sky” — and whether it can be tied to a historic eclipse.The Greek astronomer Hipparchus used the solar eclipse for calculating the distance between earth and moon, which he told was about 429,000 km. Surprisingly, its just 11 percent more than what scientists accept as the average distance between earth and moon. The element Helium was also discovered during a solar eclipse.A painting about the solar eclipse from Italian painter Giulio Ferrario(1842). Pretty funny when you imagine all of this happening in ancient times ain’t it?The science behind solar eclipses.I’m pretty sure the readers of this blog know how a solar eclipse happens right? So I’m not gonna bore you with the basics. We are gonna go pretty deep in this one, right into the juicy stuff. But you might say, “c’mon! Its just an eclipse! What’s so interesting in it?”. For that I’ll simply reply, “You’re in for a ride!!”Geometry of an eclipse.Every school boy knows why a solar eclipse happens! A solar eclipse(Partial, Total or Annular) occurs when the moon comes between earth and the sun. This occurs only on new moon days. The solar eclipse becomes total in those areas of the earth where the shadow of the moon (called umbra)is swept. The size of this shadow is about 260 km. There is a remarkable coincidince that makes total solar eclipses occur. The sun is about 400 times bigger than the moon, but the moon is 400 times closer top the earth than the sun(How cool is that!!). We are indeed very fortunate to have this celestial coincidence.But why don’t we have a solar eclipse on every new moon day ?The reason behind this is the peculiar(but interesting!) nature of the orbits of earth and the moon. You see, the orbit of the moon is ‘wobbly’ The plane of orbit of the Moon around the Earth can change its inclination to the Earth’s orbit around the Sun by about 5 degrees. The points where the orbits of the moon and earth intersect are called ‘nodes’. A solar eclipse can only occur when the sun is near one of the nodes. During the year, the sun crosses the nodes of the moon twice and this is when solar eclipse can happen. A solar eclipse must occur each time the Sun approaches the node about every half year. An eclipse alert begins whenever the Sun is within about ± 15 degrees of the node and lasts for about a month. It is possible to have two partial solar eclipses within a month, when the Sun is in the vicinity of the nodes. The closer the Sun is to the node, more central is the eclipse. If the Sun were within 10 degrees of a node, a central eclipse should occur somewhere on the Earth. Depending on the moons distance from the sun, the eclipse can be annular or total.Wait wait, does this mean that eclipses always occur at fixed timed in a year?Sadly, no. The eclipse year does not correspond to a calender year. This is due to an effect called ‘regression of nodes’ which is caused by the tidal effects of the sun and the earth in the moon’s orbit. To put it simply, the moon’s orbit spins with the moon. The change amounts to 19.4 degrees per lunar month and the eclipse year is shorter than the calendar year by 18.62 days. This results in the migration of eclipse seasons by 18.62 days every year.Check out this video for visual representation of regression:Ok that’s cool, but exactly how many eclipses can we see in a year?We have seen that eclipses occur in 2 seasons per year. Since the calender year is longer than the eclipse year by 18.62 days, we can have 2 1/2 eclipse seasons a year. As 2 eclipses , both partial, can happen a month apart in one season, we can have at-most 5 solar eclipses (4 partial and 1 central in one year). This is only for the partial and annular eclipses . The total eclipses are pretty rare, and we can calculate why.The area of an eclipse path which is typically 10000 km long and about 150 km wide is 1500,000 sq cm. The Earth’s surface area is\\(4\\pi * (6400)^2 = 5.147×10^8\\) \\(km^2.\\)The probability of us being on the path of a total eclipse is given by the ratio of the two, which is 1/343.Total eclipses occur on an average of one every 1.5 years . Therefore one could expect to see a total eclipse at a particular location on the Earth once in 343×1.5 = 514 yrs.Bonus content!Take any solar eclipse date and add 6585.32 (18 yr 11.3 days). That date will also be a solar eclipse! The reason for this repetition is that in 6585 days, the moon completes 223 lunations(lunar months) of 29.53 days, while the sun completes 19 eclipse years of 346.62 days each and both return to the same relative positions near the nodes .Such cycles of eclipses form a Saros family. There are many such Saros cycles concurrently in existence.Scientific studies during solar eclipses.Discovery of Helium.Now lets steer from geometrical to the practical. Apart from the glorius sights, the total solar eclipses also shown the previously hidden parts of the sun. Yes, you guessed it right, it’s the Corona, the mysterious outer atmosphere of the sun. At other times, even if the Sun is blocked out, the light from the bright solar disc (called the photosphere), gets scattered into the line of sight by molecules and dust of the terrestrial atmosphere and this scattered light is still several orders of magnitude stronger than the faint corona. So from the surface of the Earth the corona can never be seen. But due to the advent of the space technology, corona has become more accessible but from the space. Many spacecrafts keep a close watch at the sun’s corona. Some of them being Solar and Heliospheric Observatory (SOHO) and Transition Region and Coronal Explorer (TRACE).Scientific studies of the solar eclipses began with the eclipse of 1842 which crossed southern Europe. One of the most scientifically rewarding eclipses took place in 1868 in peninsular India. An American astronomer W.W Campbell made an important discovery during this eclipse, that the corona of the sun is strongly polarized. This observation indicated the presence of material particles in the corona. Today we know that these particles are nothing but electrons, but the electron was not yet discovered in 1868. Later the French spectroscopist Jules Jansen observed the bright prominences in corona and found a way to observe them even outside the eclipses. Later the English Later Lockyer physicist carefully examined the spectrum of prominences and found a yellow line which he could not attribute to any known element. He invoked a new element to explain the presence of the yellow line and called it helium after ‘helios’ meaning the Sun in Greek.A spectrum of Helium element during Solar eclipseGeneral theory of Relativity: ‘Bending’ of starlight near the sunOne of the most famous series of experiments conducted during total eclipses was to test the predictions of the general theory of relativity formulated by Einstein.According to the theory, the maximum deflection of the starlight near the sum would be 1.75 arc seconds. The deflection would decrease in inverse proportion to the angular distance of the star from the center ,of the Sun. The experiment would consist of photographing as many stars as possible in the vicinity of the Sun during totality followed by photographing the same field about six months later when the Sun is no longer in that part of the sky . Since the measurements of extremely small angles are involved, the measurements should be very accurate. Atmospheric aberrations, distortion of stellar bodies due to minute defects in the cameras would add further complications. This challenge was taken up by the young scientist Arthur Eddington. After measurements, Arthur found out the deflections ranging from 1.55 to 1.94 arc seconds with a mean error of 0.3 seconds. This essentially proved the General theory of relativity. That was a momentous occasion in the history of mankind.The Future…Total eclipses of the Sun will continue to occur with clock like regularity for at least another 600 million years providing the earthbound eclipse chasers with changing views of the beautiful corona, as the Sun goes through its activity cycles.As each totality passes into history one is left recalling the immortal lines of John Keats in Endymion:“Thing of beauty is a joy for ever: Its loveliness increases; it will never Pass into nothingness”." } , { "title": "Persieds Meteor Shower 2020", "url": "http://blog.sedscelestia.org/Persieds-Meteor-Shower-2020/", "date": "June 20, 2020", "category": "Uncategorized", "tags": ["Perseids","Meteors","Skywatching"], "author": "Yashraj Patil", "content": "Since the beginning of mankind on our blue planet, as old as our time goes, we have looked with awe and marveled at those bright streaks of lights that whiz past the black canvas on a starry night. The meteor showers are extraordinary cosmic events that have had impacts on many generations of civilizations and shaped their beliefs to carve out beautiful pieces of myths and legends. Evolving from bad omens to good luck over centuries of rise and fall of cultures, today we look at them with a logical perspective to explain their interesting origins to their dooming fate.One of these majestic events, probably the most famous one, the Perseid meteor shower will be active from 17 July to 24 August. The peak of the meteor shower in Mumbai, India is expected to be on the night between 12 and 13 August. If you are lucky to have clear skies and dark surroundings, chances are you can see more than 50 meteors. During the peak, there are anticipated up to 150 meteors per hour.The most appropriate time to view these shooting lights would be from 22:07 IST to 00:52 IST. The radiant, the origin of meteors, will continue the shower till 14:48 IST on 13 August but the visibility would be greatly affected after the moon starts its reign over the night sky from 00.52 IST onwards. Though the moon washes out many of the meteors, you might still catch 5-6 bright ones with good luck.Credits: Casey Horner(Unsplash)Even if the moon messes up the shower for you, don’t worry, cause you can still catch a night-long view of breathtaking meteors from 17 August onwards when the moon no longer visits during the dark hours.To find out the peak hours of the meteors at your location, visit www.timeanddate.comNow how to spot the radiant point for the Perseid meteor shower?If you are able to trace back a few of the meteors you see, you will find that they lead to the same spot in the sky. That origin of the meteors is called the radiant point and in this case, it will appear to be in the Perseus constellation, famously named after Perseus, the famous Greek mythological hero. Though keep in mind, the meteors are not actually originating from near the stars in the constellation itself. Those stars are light years away, but the meteors are way closer to you. They are named so only because their radiant seems to lie in the Perseus constellation if seen from Earth.So what causes this beautifully ethereal meteor shower?It all starts with the timeless journey of a clump of rock and ice that travels intricately through our solar system, visiting the Earth every few years. This celestial object is called a comet. Once a comet is set in motion around the sun in a set path, it continues its journey endlessly through the vast emptiness of space.The comet that causes the beautiful Perseids is named the 109P/Swift-Tuttle and its orbit intercepts Earth’s orbit at a point in space. During the comet’s journey in the inner solar system, as it approaches the Sun, the immense heat causes the ice to warm up and soften, which in turn leaves a trail of fresh comet material in its orbital stream. Every year from mid-July to August end, our Earth passes through this very orbital path intersection. That’s when the show starts as the debris from the Comet Swift-Tuttle slam into Earth’s upper atmosphere at the speed of more than 200,000 km/hour and we watch as the fireworks commence. The peak of the shower starts when we get to the dense portion of the comet debris around mid of August. The few strong ones that survive the long fall burning through our atmosphere, end up hitting the ground and are called meteorites.The Comet Swift-Tuttle last reached the nearest point of its orbit to the Sun, the perihelion, in December of the year 1992. As the comet travels along its orbit extending beyond Pluto’s orbit, its whole journey to complete a full round and return take a staggering 133 years! Therefore, if you have missed the comet sighting in 1992 and are reading this article, chances are you won’t be watching it return in July 2126. But it has left us with the amazing Perseids nonetheless.Courtesy NASA/JPL-CaltechIf you are to plan a night long observation for the Perseid, there is no need for any equipment to carry with you. Find a secluded place, away from the constant buzz and city lights, somewhere dark and peaceful to set up your camp. Just lie down under the stars and give your eyes about 20 minutes to adjust to the setting. Relax and wait for the sky to light up!Go check out his blog for many more interesting articles like these from Yashraj!!" } , { "title": "Astronomy In Ancient India", "url": "http://blog.sedscelestia.org/Astronomy-in-Ancient-India/", "date": "June 15, 2020", "category": "Uncategorized", "tags": ["Ancient","Aryabhata","Bhaskara_I","Brahmagupta","History","Jantar_Mantar","Lagadha","Physics","Sawai_Jai_Singh","Science","Varahmihira"], "author": "Sanika Chepe", "content": "Yes, you read that right, but trust me, there’s more to it than all those forwarded Whatsapp messages about “the distance of Earth from the Sun being the same as was predicted” It is surprising how much our ancestors knew about astronomy and how little we know of their findings! It is time we pause and ponder over their brilliance as they looked up to the heavens.The first mention of astronomy in India was in the Vedas, the oldest scriptures of Hinduism, way back in 2nd Millenium BC! Back then, Astronomy was known as “Khagola-Shastra” or the Science of Cosmos (Khagola meaning Cosmos and Shastra meaning Science). Although the oldest Veda manuscripts are dated 1500BC, we must understand that they were in existence well before that and were passed on through recitation as they lacked a persistent storage medium like paper. The Vedas were born during the transition from the Neolithic Age to the Bronze Age, marked by the beginning of Agrarian civilizations, with the Indus Valley Civilization in India. Back then, the farmers lacked a system to keep track of the seasons and found their solution as they noticed the periodic change in the pattern of stars and were thus motivated to delve deeper into the field of astronomy.Possible association of the Harappan seal with the night sky at sunset at the onset of the monsoon season.Now that we know about the origin of astronomy in India let us talk about the contributions of various scholars in this field. However, before we do that, it is necessary to mention a specific category of Astronomical works of Ancient India, the revelations. The authors of these works hid their identities with the motive of making their astronomical theories and calculations acceptable to the common man, making them look like direct transmissions from the Gods. In Indian mythology, there are seven celestial bodies: the Sun, Mercury, Venus, Mars, Jupiter, and Saturn along with two other “evil” ones, Rahu and Kethu which made the Sun disappear from time to time (the Solar eclipse!). The Prehistoric Indians were able to differentiate these celestial bodies as they seemed to move relative to other stars and were comparatively brighter. They were also able to predict the phenomena of Solar and Lunar eclipses precisely!Now, let us review the breakthroughs made by ancient Indian astronomers. The major contributors were prominent astronomers like Lagadha, Āryabhaṭa, Brahmagupta, Varāhamihira, and Bhāskara I.Lagadha was the author of Vedānga Jyotiṣa, the earliest astronomical text. Astronomy was a discipline of Vedanga or one of the “secondary disciplines” associated with the study of the Vedas. The Vedānga Jyotiṣa has connections with Indian astrology (or Jyotiṣashastra) and lists several astronomical attributes generally applied for timing social and religious events. It also details astronomical calculations along with significant aspects of the time and seasons, including lunar months, solar months, and their adjustment by a lunar leap month of Adhimāsa (an extra month added to the calendar after every 6years). Ṛtús also described as yugāṃśas (or parts of the yuga or a conjunction cycle) are discussed as well.Vedanga JyotishaCourtesy: “Sarwang”, Published by Adivasi Lok Kala Evam Boli Vikas Academy, Madhya Pradesh Sanskriti Parishad, India.Āryabhaṭa was the first of the principal mathematician-astronomers from the classical age of Indian mathematics and Indian astronomy. His works include Āryabhatīya and the Āryabhaṭasiddhānta, which greatly influenced the Indian astronomical tradition and influenced several neighboring cultures through translations. He explicitly mentioned that the Earth rotates about its axis daily and that the apparent movement of the stars westward, is a relative motion caused due to its rotation, contrary to the then-prevailing view that the sky rotated. He stated that the Earth was spherical, with a circumference of 39,968km (24,835 miles), just off the currently accepted value of 40,074km by an incredible 0.27%! He calculated the rotation of the Earth referencing the fixed stars (a.k.a sidereal rotation) as 23 hours, 56 minutes, and 4.1 seconds; the modern value is 23:56:4.091. Similarly, his value for the sidereal year at 365.25858 days is an error of 3 minutes and 20 seconds over the length of a year (365.25636 days). Such accuracy in his calculations is astonishing, considering the lack of an accurate device to measure time or a standard unit of length, during those times. Solar and Lunar eclipses were scientifically explained by him in terms of shadows cast by and falling on Earth. Among other predictions, he even provides the calculations for the size of the eclipsed part during an eclipse! He also mentioned that the Moon and planets shine by reflected sunlight. He was one of the first to assign the start of each day to midnight. Damn! That’s one long list! We haven’t even talked about his mathematical works! After all, he invented Zero!AryabhataIllustration: AlamyBrahmagupta, in his works, reinforced Āryabhaṭa’s idea of a day beginning at midnight. He calculated the instantaneous motion of a planet, gave correct equations for parallax, and some information related to the computation of eclipses. He also theorized that all bodies with mass are attracted to the Earth. (Around 665 CE, approximately 2351 years before Newton proposed the Law of Gravitation in 1687 AD!)BrahmaguptaSrc: UnknownVarāhamihira was an astronomer and mathematician who studied Indian astronomy as well as the many principles of Greek, Egyptian, and Roman astronomical sciences. His treatise is a summary drawing from different knowledge systems.VarahmihiraSrc: BharatkoshBhāskara I authored the astronomical works Mahābhāskariya (Great Book of Bhāskara), Laghubhaskariya (Small Book of Bhaskara), and the Aryabhatiyabhashya —a commentary on the Āryabhatīya written by Āryabhaṭa. Planetary longitudes, heliacal rising and setting of the planets, conjunctions among the planets and stars, solar and lunar eclipses, and the phases of the Moon are among the topics Bhāskara discusses in his astronomical treatises.Bhāskara ISrc: UnknownNumerous other astronomers of the ancient and middle ages have made valuable additions to the discipline of Astronomy. Some of their devices can even be seen today, like the famous Jantar Mantar observatories in Jaipur, New Delhi, Ujjain, Mathura, and Varanasi constructed by Sawai Jai Singh (1688–1743 CE).Jantar Mantar, Jaipur, and Sawai Jai SinghSrc: UnkownIt is very noteworthy that Indian astronomers discovered all these facts 1,500 years ago, i.e., ten centuries before Copernicus and Galileo, the pioneers of European astronomy. India had a significant influence on other civilizations’ early development in the field. They have left behind a great legacy and motivate today’s astronomers to keep exploring and experimenting. I know that there are numerous exciting topics in Modern astronomy to write an article on, but this is a topic that exceedingly fascinates me and fills me with profound national pride. I think that one of Mr. Einstein’s quotes sums up my motive to write this article pretty well: “Learn from yesterday, live for today, hope for tomorrow. The important thing is not to stop questioning.”References Ancient Indian Astronomy (CosmoQuest) Harappan Astronomy (TIFR) Wikipedia - Indian Astronomy Wikipedia - Aryabhata Header Image Credits: FlickrThis work is licensed under the Creative Commons Attribution-ShareAlike 3.0 License." } , { "title": "Understanding Telescopes and Binoculars - Part2", "url": "http://blog.sedscelestia.org/Understanding-Telescopes-and-Binoculars-Part-2/", "date": "June 8, 2020", "category": "Uncategorized", "tags": ["Skywatching","Telescopes","Optical_aid"], "author": "Avdhoot Bhandare", "content": "Part 2: Tremendous TelescopesSo, I’m assuming you’ve read the first article of this series, and are now the proud owner of your very own pair of shiny, cool binoculars! Great! But if you’re anything like me, you want the real stuff (wink). The stuff that will get you as high up as the stars themselves, so close that you can reach out and touch them (and get vaporized into a gazillion particles too, but I try not to think that far ahead). I’m talking, of course, about telescopes!Telescopes are a bit complicated. Okay, maybe they’re very complicated, at least to the uninitiated. But don’t worry, if you understand the principles, and practice a bit, you can use one too, and I assure you, the results will blow your mind. Telescopes, even small, backyard ones, are capable of showing you some of the most beautiful and amazing things in our wonderful universe. You can glimpse some of the most awe-inspiring things in the night sky, stuff that you only read in some book or article, stuff that would not be out of place in a fantasy novel. You can have all of that, if you learn how to use a telescope; which brings us back down to earth, to the basics.Now, since you’ve read the previous article, let’s try to build on your understanding. Imagine that we take your shiny, new, cool pair of binoculars, and, umm, cut it in half right down the centre (sorry!). Take one half, and make it bigger. Way, way bigger, until it’s as big as you are (if you’re about 4 feet tall). Next, since it’s too heavy to use with your hands, you mount it on a stand. What kind of stand, if it has 3 legs, 4 legs, or no legs at all, we’ll see later. Now, if you are used to getting down to your knees a lot, you can leave the eyepiece down at the bottom of the tube. Since it is bigger, it’s now more difficult to find stuff in the sky, so you take the other half of your binoculars, and stick it on the side of your imaginary telescope. You can use this to find the rough position of objects, and then use the main eyepiece to make final adjustments. Et voila, you have now achieved a refractor, or Galilean telescope!Seriously, though, putting all jokes aside (for now), a refractor is just that; a long tube with lenses at either end. A convex lens acts as the objective, collecting light from objects, which then passes through a concave lens at the other end of the tube and makes its way into your eyes. Since it’s the bigger, badder version of the binoculars, it has much higher magnification, which, if you remember, results in a really tiny field of view. Because you’re looking at such a small part of the sky, it can become very difficult to actually find stuff. Hence, all telescopes come equipped with a smaller, mounted scope or simple cross-hair, like a sniper rifle. This is called the finder scope, and as the name implies, it helps you find the object you’re looking for. This entire apparatus is attached to a mount that can move smoothly so that the telescope can point to any part of the sky. Refractors are sturdy and need little care and maintenance, since the lenses are quite strong and the inside of the tube is sealed off from the atmosphere. However, lenses are quite heavy, and get heavier and heavier as the aperture increases. Another disadvantage of using lenses is that lenses bend the light, and different wavelengths bend differently. It looks very pretty when you make a rainbow through a prism, but here is creates quite the problem. This effect, called “chromatic aberration”, is mitigated using correcting lenses, but is a fundamental flaw of using lenses.Now, continuing with our maiming of your binoculars, imagine that you have a crazy brother. He has his own binoculars, and since he’s got nothing to do he’s copied you so far, but he’s lazy, and gets bored easily. So, just for kicks, he modifies the design a bit, throwing out the objective and putting in a mirror at the base of the tube instead, and another smaller mirror at the top, pointing sideways. He now has a smaller, fatter tube, with a mirror inside and the eyepiece on the side. Later that night, you both head out to test your instruments. You’re waiting outside while two servants haul your heavy refractor out into the open, while your brother saunters over, his telescope nonchalantly perched on his shoulder. You laugh scornfully at his absurdly fat telescope, with nothing on the top as you look inside, seeing an ugly warlock looking back at you. You jump back in horror, but realise it’s a mirror (hey, wait a minute) and head back to your own refractor which is still being set up, thinking that his design will never work. One last look at him and you see his smug face as he plops his bazooka-esque apparatus down and leisurely swings it around, as you impatiently wait for your servants to maneuver you unusually heavy telescope onto its stand.Okay, so coming back to the present, your imaginary brother was Newton (surprise!) and his telescope, logically enough, is called a Newtonian, or reflector. The light is gathered using a mirror instead of a lens, which has several advantages. It isn’t as heavy, the light isn’t lost in the lens, and the eyepiece can be attached further up the tube, which makes the viewing angles much less awkward. It isn’t all sunshine and daisies, though, as your mirror is exposed to the atmosphere, and hence dust, water, etc can cloud and damage the mirror, the optical components are more prone to go out of alignment, and temperature changes can also make a difference in the clarity of the image. Overall, this design is a bit more delicate, as the mirror can shatter, but it is also much lighter, and easily portable and gives a brighter image than the refractor. Reflectors are cheaper to make, and as big as you want them. There is another variation of the reflector called the Cassegrain telescope. The major difference is that the Cassegrain still has its eyepiece at the bottom of the tube, seen through a hole in the objective mirror.Finally, let’s move on to what your younger brother is doing. Oh, you don’t have a younger brother? Well now you do. And he’s obsessed with Dragon Ball Z. One night you catch him in the store room where your telescopes are kept. He’s moving around a lot with your precious instruments, for some strange reason. Suddenly there’s a flash of light, and a big BOOM!!! Horrified, you run in to see what has happened, and your eyes fall on this strange, new telescope standing in the middle of the room. Of your brother, there’s no sign (good riddance, you think). Cautiously, you step closer and examine this new telescope, It’s very similar to the Cassegrain we talked about earlier, with a mirror at the bottom, another smaller mirror in the center of the aperture, and the eyepiece way down at the bottom. It’s also much shorter and fatter, and has a lens across the aperture. This telescope, born of a fusion dance of the reflector and a refractor, is called a Catadioptric telescope.Essentially, that is what it is; it makes use of both lenses (dioptrics) and mirrors (catoptrics) to present the image. Similar to the Cassegrain, the light is reflected twice inside the tube, hence the size of the telescope is much shorter than the other varieties. This makes the catadioptric much more compact and portable. The lens and mirrors are not that complicated to make, and hence the telescope is cheaper than you’d expect. However, as any optical engineer will tell you, “Every optical design is always a compromise!” The catadioptric suffers from many of the pitfalls of the reflector telescope, as it is delicate, goes out of alignment more often, and as an added problem, the construction of this telescope is more complex, and as such more difficult to solve it’s problems.Now that you know about the 3 main types of telescopes, let’s move on to the finer details of a telescope. Similar to the binoculars, the aperture is a very important aspect of the telescope, as it governs how bright your images will be. Next, the focal ratio of the objective decides a lot of factors, like how long your telescope is going to be, and the magnification. However, we rarely look at the focal length by itself; we instead focus (hah!) on a number called the focal ratio. The f-ratio is the focal length divided by the aperture and is probably the most informative and important factor for a telescope. A larger f-ratio implies more magnification, but a narrower FoV and a dimmer image, which is great for viewing brighter stuff that has a lot of detail, like the moon, or the planets. A lower f-ratio, on the other hand, collects more light, shows more of the sky, but gives less magnification. A lower f-ratio is usually desired when viewing extended objects like nebulae and galaxy. It is also important for your telescope to pick out small details; this ability is called the resolving power. It is directly proportional to the aperture; a bigger aperture can distinguish more details. And finally, we come to eyepieces. Contrary to binoculars, ‘scopes come equipped with multiple, interchangable eyepieces, as eyepieces decide how magnified the image will be. The formula for magnification is simple; F/f, where F is the focal length of the objective, f of the eyepiece. There are limits to the magnification, however, as every small movement and disturbance is magnified when using a telescope. After a certain point even extremely minute disturbances like an imperceptible breeze, or even the breath of the user, can make the view useless. Usually, a magnification of 50x aperture in inches is the limit, though this isn’t a set rule, more of a guideline.You made it to the end, great! Well you know now the most popular types of amateur telescopes, and how they work! Am I ready to wield a telescope then, sensei, you may ask. Not quite yet, though you’re well on your way. Next we’ll understand how telescope mounts move and work, since they’re as important as the telescopes themselves, and a good understanding of their co-ordinate systems will lead to a much cleaner and enriching view of the night sky." } , { "title": "Understanding Telescopes and Binoculars", "url": "http://blog.sedscelestia.org/Understanding-Telescopes-and-Binoculars/", "date": "June 1, 2020", "category": "Uncategorized", "tags": ["Skywatching","Telescopes","Optical_aid","Observations","Coordinate_system"], "author": "Avdhoot Bhandare", "content": "Part 1: Brilliance of BinocularsThe night sky is a treasure trove of wonders and secrets that had me enthralled ever since I was a kid. Random, scattered stars in the sky resolved themselves into majestic constellations as I learned more about the sky. Eventually, I discovered galaxies, star clusters, nebulae and much more as I “followed the night”, so to speak, and wanted beyond all else tolook at these Deep Sky Objects (or DSOs, for short). Here, like many others, I hit a wall. Photos taken by huge telescopes floating in the sky above us were beautiful enough, but for me it wasn’t enough. I wanted to look at them with my own eyes. I might not see an image as grand as seen by Hubble, but it would be worth much more to me. How, then, should one proceed?Here, many budding amateur astronomers would get confused. Should I buy a pair of binoculars? Maybe a telescope? What kind, though? The long, narrow ones that they show in pirate movies, that’s a telescope too right? Should I get me one of those, an’ a wooden leg, an’ a parrot too, for the complete pirate experience? Or perhaps the more commonly known generic telescope that is attached to a 3 legged stand? Which of these is the best for me? Is it too costly? All of these questions can bog down a very promising and interesting journey to the stars, but hang on, me hearties, it’s not as complicated as you think!There’s a looooot of stuff out there for an astronomer, but if you want to be a standard, backyard astronomer, then binoculars and telescopes are the two most common instruments that you will use. Which of these you should buy first depends on how much effort and investment you are willing to put in. A pair of binoculars, although a bit complicated to choose the right model, is quite easy to use. A few hours of practice and you’re good to go! Telescopes, well, they require quite a bit of practice and dedication to get the hang of, and generally take more time to set up and use. However, having got that out of the way, once you learn to use either of them, it’s well worth the effort!Let’s start with a basic understanding of how these instruments work. All binoculars and telescopes have a large opening (or 2 large ones, in the case of our binoculars), that collect more light than our eyes do. More light means that light from fainter objects also reaches our eye, which we otherwise wouldn’t have been able to detect. This opening is called the aperture, and is a very important aspect of these instruments, as it will decide many factors, like how faint objects can we see, how big and heavy the lenses will be, what is the maximum magnification, etc. But more on that later. Once the aperture collects the light, it is “processed” by some combination of lenses and mirrors, magnifying the image in the process.In the case of binoculars, we have 2 lenses, one called the “objective”, since it collects light from the object, and the other is the “eyepiece”, the one that we look into. The objective is the same diameter as the aperture, but the eyepiece is quite small, usually similar to the size of your eyes. As binoculars get bigger, it’s difficult to fit the eyepieces such that they are in line with your eyes, so the light is passed through “porro prisms” to adjust the path of light. These prisms are what give bigger binoculars the flared out structure.Now, for the important part; what factors are the most important when looking for a good pair of binoculars? There are a huge number of factors and ratios that make up these instruments, but the major ones are the aperture, magnification (and hence field of view) and quality of lenses. The aperture, as discussed before, dictates the amount of light gathered; more light implies visibility of fainter objects. Obviously, we want as much light as possible, but the bigger the aperture, the bigger the objective lens gets, and in general we have a bigger and heavier instrument, which is cumbersome and difficult to hold up for long amounts of time. An aperture of around 50-70mm is desirable, as anything bigger than that will be too heavy to practically use while handheld (even 70 mm is pushing it!). Of course, binoculars with larger apertures exist, but they must be mounted on a tripod to get clear images.Secondly, magnification is a bit of a debate; some people prefer seeing larger objects with more detail, while others like to see a larger part of the sky. Here is where the field of view comes in. It is basically how much sky can you see at your current magnification. FoV is generally expressed in degrees, and it shares an inverse relationship with magnification; larger the magnification, lesser the FoV. Although this might be down to personal preference, as a rule of thumb, if your binoculars are going to be your primary instrument, it would be better to choose one with higher magnification. If you plan on having a telescope too, then it is much better to get a pair of binoculars with a wider field of view, since the telescope will show you all the detail you need, and the binoculars provide a much-needed wider view of the sky. 8-12x is a good range of magnification to choose from.Finally, we come to lenses. Buying a pair of binoculars with good quality lenses is of paramount importance, but often overlooked. Lenses decide how well the light is collected and processed, and finally how good an image you get. Although better lenses makes the binoculars costlier, it is very well worth the money in the long run. Cheaper lenses have a host of problems pop up as they grow older, like colours splitting up, objects at the edge of your FoV getting distorted, etc. Buying a pair with good quality, fully multi-coated lenses with BAK-4 prisms will shelve all these problems for a good 8-10 years! So if you have the budget, definitely go for better quality lenses. Apart from these, there are a number of other factors too, like eye relief, weather durability, etc. Although these are significant too, the major factors are aperture, magnification and lens quality. Generally a good manufacturer will provide good lenses, and better overall quality, so try to stick to the well known companies like Orion, Bushnell and Celestron. I have an ancient pair of binoculars of the Cobra Breaker series; they are well over 15 years old, but the lenses still have their coating intact, and they still deliver crisp and clear images, and I use them almost every week. That is how durable a good pair of binoculars can be!Summarising, you should buy binoculars according to how much use they will be put to, and whether they are your main instrument for stargazing. 8×48 – 12×70 is a decent range to pick from (00×99 means 00 is magnification and 99 is the aperture of the objective). I’ve put links to a few binoculars at the end of the article, do check them out to understand the varieties!A 10×50 Orion piece that is very spectacle-friendly.10×50 Orion BinocularsCelestron’s 10×50 binoculars: Although these are meant for terrestrial viewing, they are just as good for astronomy. The aluminium body makes it much lighter, but it is a bit costiler due to having a sturdier build for use in the outdoors.Celestron’s 10×50 binoculars12×60 Skywatcher by Celestron, A bigger, heavier model.12×60 Skywatcher by CelestronA 15×70 monster by Meade, another good producer of astronomy equipment. Bigger models are tripod compatible, so you can use them without having to hold them up.Meade 15*70 AstrobinocularsAnother very popular combination, 20×50 by Bushnell. It has fewer lens coatings so is a bit cheaper, if your budget is tight!Bushnell-20*50" } , { "title": "“What to expect when a giant cloud of gas collides with your galaxy?”", "url": "http://blog.sedscelestia.org/Giant-Cloud-of-gas/", "date": "May 25, 2020", "category": "Uncategorized", "tags": ["Myth","Smith_Cloud","Physics"], "author": "Shounak Bhattacharya", "content": "When scientists were working to discover more about the universe and especially our own galaxy in the early 1960s, one of the few celestial discoveries of the time included the Smith’s Cloud. In 1963, when discovered by doctoral astronomer Gail Smith, it was believed to be just an extension of the Milky Way, and nothing was known about its motion. It was only decades later that Astronomer could make a detailed image of it and calculate its velocity and exact composition. Smith’s Cloud is a large, high-velocity hydrogen gas cloud in the constellation of Aquila. It is 11,000 light years long and 2,500 light years wide. It is about 8,000 light years away from our galaxy’s plane at an angle of about 45 degrees. However, the initial assumption that Smith’s Cloud is an extension of the Milky Way was proven wrong when it was discovered that it is heading for a collision with the Milky Way at a velocity of more than 240 km/s and is already interacting with the gases at the edges of the galaxy.Ever since its independent nature was discovered, astronomers theorized that Smith’s Cloud is merely an interstellar cloud which travelled across space and was caught in the gravitational pull of the Milky Way. This would have been true if Smith’s Cloud was composed of only hydrogen and helium. In order to determine the exact origins of the Cloud, astronomers decided to calculate the Cloud’s exact chemical composition. Using three galaxies which are billions of light years away and lie in the same direction from earth as Smith’s Cloud as the source of ultraviolet light, astronomers used the Hubble Telescope’s Cosmic Origins Spectrograph to measure the amount of ultraviolet light that the Cloud absorbs. From the spectrum of ultraviolet light obtained, the amount of sulpher present was calculated, since the amount of sulpher allows scientists to estimate the amount of other, heavier elements using the sun’s composition as a reference. The most interesting part is that the percentage of sulpher in Smith’s Cloud matches that in the outer disk of the Milky Way. Thus, it is proven that Smith’s Cloud was formed of materials ejected from the Milky Way and is now falling back into the galaxy. If Smith’s Cloud has formed of materials from our galaxy, it could mean that often such clouds are formed from galaxies which then return to the galaxy, crashing back onto another part of the galaxy.In such a manner, a lot of galaxies could “recycle” such clouds of unused gases. Furthermore, the fact that this cloud of gas is heading back towards the galaxy has caused great excitement in the scientific community since it could mean a new chain of star formation. In 2007, astronomers Felix J. Lockman, Robert A. Benjamin, A. J. Heroux, Travis Fischer and Glen I. Langston presented to the 211th meeting of the American Astronomical Society their results from detailed observations of Smith’s Cloud using the Green Bank Telescope. Their findings concluded that Smith’s Cloud is heading towards the plane of the galaxy and would crash into the Perseus arm of Milky Way in about 30 million years. This can trigger a wave of star formation, with massive stars being formed which would rush through their lives quickly and explode as supernovae. This discovery further supports the hypothesis of gas recycling by galaxies, allowing such unused gases to form more stars. On the whole, the trajectory of Smith’s Cloud has provided an insight into the life cycle of galaxies and their interaction with interstellar matter. Moreover, detailed data from the Green Bank Telescope allowed astronomers to follow the trajectory of Smith’s Cloud backwards in time. According to simulations, about 70 million years ago Smith’s Cloud passed through the plane of the galaxy with little or no loss of matter. Also, research papers submitted in 2009 conclude that Smith’s Cloud may be a hundred times more massive than earlier estimates, putting its mass at around 300 million solar masses. A gas cloud that massive cannot survive a collision with the Milky Way and should disintegrate on collision.Despite that, Smith’s Cloud seems to have survived such a huge collision in the past and is again headed for another collision (though researchers believe that Smith’s Cloud may not survive this collision; tidal forces have already begun to tear it apart). The fact that Smith’s Cloud survived such a collision led astronomers to theorize that Smith’s Cloud is encapsulated in a dark-matter “halo”, which protected the Cloud from the destructive tidal forces and led it to its current trajectory. This theory, if proven, could explain how the earliest stars in our galaxy were formed. Furthermore, this theory also leads to the possibility that Smith’s Cloud, in fact, is a failed, dwarf galaxy which may have been formed from the gases left over from the initial wave of star formation in the Milky Way, and would allow astronomers to estimate a lower limit on the size of galaxies in general. On the whole, Smith’s Cloud is one of the most unique objects in the night sky which, due to its closeness to us allows us to study it in great detail, and provides us with an insight into the history of the Milky Way and how our galaxy, and in general most galaxies, operates. Further research into this unique phenomenon will provide us with more knowledge of our universe." } , { "title": "Our Universe In The Radio Spectrum", "url": "http://blog.sedscelestia.org/Our-Universe-in-the-Radio-Spectrum/", "date": "May 18, 2020", "category": "EM_Cosmology Science", "tags": ["CMBR","Cosmic-Microwave-Background-Radiation","EHT","GLEAM","History","M87","Radio_Spectrum","Science"], "author": "Abdul Jawad Khan", "content": "Often we have looked up at the night sky and seen the hundreds of tiny dots blanketing the sky. One look at these stars, planets, nebulae and galaxies, and one is left marveling at their beauty. However, what we are able to see through our eyes and our optical telescopes, is but a small portion of a very large and very amazing universe. This is because visible light occupies a small part of the electromagnetic spectrum, and if we tune our instruments to ‘see’ the other regions of the electromagnetic spectrum, we are greeted to new and wondrous ways of looking at our universe and observing how it behaves. One of the most interesting regions we can view the universe in is the radio spectrum, and it is so interesting because although bright stars and galaxies do emit visible light, almost everything in the universe, from gas clouds to planets, emit radio waves and so being actually ‘visible’ in the radio spectrum. Thus, viewing the universe in the radio spectrum essentially allows us to see celestial objects which we couldn’t through the visible spectrum. As a bonus to that, radio waves are much less scattered than light rays, and thus can travel further without losing much of their information, hence becoming a better means of information about their sources. One more advantage that the radio spectrum offers is that it enables the study of the early stages of the universe. This is because the farther we look into the observable universe, the farther back in time the electromagnetic radiation coming from those regions is, and this radiation, although originally in the visible and infrared spectra, has been red-shifted to the radio spectrum. Thus, radio astronomy has become an indispensable tool in studying the cosmos today, but how did it all begin?Src: Wallpaper FlareThe Discovery of the Radio SpectrumSrc: Radio Telescopes - lumenlearningKarl Jansky and his radio-wave receiverThe utility of radio waves in astronomy and astrophysics was found by accident in 1933 by Karl Jansky, who was then working for Bell Laboratories on a phone system that worked across the Atlantic Ocean. However, during certain times of the day, a ‘hiss’ or a static sound was observed in the background of the calls made. Karl Jansky soon observed that the hiss was coming from the direction of the center of our galaxy. We know today that the center of our galaxy is a very active region, and emits a large amount of radio waves, particularly due to the presence of supermassive black holes like Sagittarius A*, but back then, this was a ground-breaking discovery. Jansky had detected radio waves from space, opening up a new, invisible universe.Credit: NIST ArchivesGrote Reber spent a decade working out of his backyard using self-built equipment, essentially the world’s only radio astronomer.Following Jansky’s discovery and subsequent research on the radio sources beyond our solar system, a man by the name of Grote Reber built his own radio telescope in his backyard in 1937, and used it to look at the whole sky and catalogue radio sources. From the data he collected, he built the first map of the ‘radio sky’, thereby ushering forward the concept of radio astronomy.Thus, radio astronomy started with accidental discoveries and backyard scientists. Today, it is one of the major branches of astronomy, spearheading the way we look at the universe. From the discovery of the Cosmic Microwave Background Radiation to obtaining the first image of a black hole, peering into the radio spectrum has led to some amazing breakthroughs.Imaging a Black HoleThe famous M87 Black Hole imageCredits: Event Horizon Telescope collaboration et al.About a year ago, the first ever image of a black hole was captured by the Event Horizon Telescope, which is actually an international collaboration that uses radio telescopes all over the world to perform Very Long Baseline Interferometry (VLBI). VLBI is basically using receivers (in this case radio telescopes) to perform interferometry over very large distances, which the Event Horizon team used to measure the emission regions and map the areas around two supermassive black holes with the largest apparent event horizons – SagittariusA* at the center of the Milky Way and M87 in the center of the Virgo A galaxy. By synchronizing eight telescopes across the world (Spain, Hawaii, North and South Americas and the South Pole) to within a fraction of a millimetre using atomic clocks, the EHT aimed them at M87 in April 2017 for 10 days. In those ten days, the telescopes recorded in total 5 petabytes of data, which was sent to a centralized location and combined to create a composite set of images, which revealed something that human eyes had never seen before – the event horizon of an actual black hole!Credit: EHT CollaborationThe EHT had to have a really high resolution so as to properly image the apparently tine black hole.Where Radio Astronomy comes into play is because these black holes are very far away, and have a lot of ‘pollution’ between us and them. Thus, light coming from them gets scattered much more than radio waves. More importantly, the accretion disks around these black holes are brilliant sources of radio waves, thus making them shine brightly in the radio spectrum. Hence, trying to image the black holes in the radio spectrum instead of the visible one lead to much better results and one of the greatest discoveries for humans.Cosmic Microwave Background RadiationThe Cosmic Background Radiation MapCredits: NASAThe Cosmic Microwave Background Radiation is electromagnetic radiation from the early universe, which can be detected in every direction. The CMB represents the ‘earliest’ radiation that can be detected. By earliest, I mean that before the creation of the CMB, the universe was so dense that photons could not travel freely, making it opaque. Thus, no radiation before the CMB has been detected, because the CMB is from the Recombinant Era, where electrons and protons interacted to form hydrogen atoms, and before which, there was just a cosmic soup of electrons and protons so energetic and so densely packed together that any photon emitted was absorbed. As the universe cooled down during the Recombinant Era, the hydrogen atoms formed were able to photons which were not absorbed and persist even today as the CMB. Due to the expansion of the universe, and having travelled for so long, the photons have lost a lot of energy and red-shifted to the radio and microwave spectrum, thus being detectable only by radio telescopes.Arno Penzias and Robert WilsonSrc: Encyclopedia BritannicaThe Cosmic Microwave Background was first detected by Arno Penzias and Robert Wilson in 1963, when they were studying microwave signals from the Milky Way. They found background noise of unknown origin in their observations, regardless of where they pointed their instruments. At first, they thought that this was because of pigeon droppings, but even after removing all the pigeons from their instruments’ environment, they were still getting these readings. Moreover, these readings were coming to be more or less uniform from all directions. Thus leading to the discovery of the Cosmic Microwave Background Radiation, which is one of the biggest evidences of the Big Bang.‘We are embedded in shells of cosmic time, and the final one, is fire.’What the CMB tells us, with its red-shift and uniformity in all directions, is that the universe has been expanding uniformly in all directions, meaning that it has to have come from a singularity or the like as predicted by the Big Bang Theory. The other contender, the Steady State Theory, which said that the universe has existed as it is forever, was thus disproven. If the Steady State Theory was true, we would not have got the CMB as being red-shifted, and it would not be uniform in all directions due to clumping together of matter to form galaxies and superclusters, and would have otherwise been in spots throughout the universe, much like the radio signals coming from the universe are today.Making a Map of The UniverseThe Galactic and Extragalactic All-sky MWA survey, or GLEAM, is one of the largest sky surveys of all time, conducted using the Murchison Widefield Array (MWA) in Australia. Although many sky surveys have been done before, and many sky-maps made, none have been of this scale. GLEAM scans the entire sky for radio waves, then identifies and catalogues their sources. Through this, astronomers have been able to find features like soap bubbles, which mark sites of ancient supernova explosions. This is where massive stars ran out of hydrogen fuel, imploded, and then exploded outward, creating a shell of radiating plasma expanding into space. In the past, astronomers have found far fewer of these supernova remnants than are needed to account for the high-energy electrons that produce the synchrotron glow of the galaxy. Fortunately, GLEAM is perfectly suited to detecting these missing remnants, solving a cosmic puzzle. GLEAM is thus being used to look for answers to some of the mysteries which have puzzled cosmologists and astrophysicists for over a decade.The GLEAM Sky Map, showing the Milky Way Galaxy, and near the top right, the Large Magellanic Cloud.Credit: Dr Natasha Hurley-Walker (ICRAR/Curtin) and the GLEAM TeamHence, we see that radio astronomy has become an indispensable tool for peering into the universe with a new set of eyes. From confirming discoveries to travelling to the edge of the universe and uncovering the mysteries that lie just beyond the reach of our eyes, looking at the universe through the radio spectrum has been a fascinating and humbling experience for us human beings, showing us that there is a huge mountain of information left to be explored and discovered.Header Image Source: Allen Telescope Array in California" } , { "title": "The Mythology of Planets", "url": "http://blog.sedscelestia.org/Mythology-of-Planets/", "date": "May 11, 2020", "category": "Uncategorized", "tags": ["Mythology"], "author": "Avdhoot Bhandare", "content": "Looking up at the night sky always inspires in me a feeling of great wonder, of silent admiration. They have been here since the beginning of time, and have seen it all. If only they could speak, the stories they could tell us! Orion, the mighty hunter, what stories might he tell, of the fascinating beasts he has slain? What would Hercules tell us, tales of his twelve labours? Would Mars boast of all the battles he has conquered, and all the kingdoms he has ground to dust? Every constellation, star and planet has a story to tell, and it is up to us to listen. But whence do these stories come from?Most of the credit of the names and stories of almost all objects in the northern hemisphere of the night sky go to the ancient Greeks and Romans. The Greeks wove their rich mythology into the stars, turning gods, heroes and monsters into constellations, and thus making them truly immortal beings. The Romans, consequently, named the planets after their gods, accurately reflecting their characteristics. Many of the constellations are involved in the same story, making the night sky an intricate compendium of myth and beauty.The planets .The mighty Greek and Roman empires were built, in large part, due to their belief and trust in their gods, whom they thought always watched over them. And who better to be the silent guardians then the planets themselves, eternal, mystical, and ever so distant yet so powerful? And hence came into being the names of the planets, believed to be the gods themselves, aiding them in all their endavours.Mercury, named for the speedy messenger god, revolves fastest around the sun;Venus, named for the Roman goddess of love and beauty, shines brightest in the sky and is the most beautiful of all planets. Many legends revolve around Venus, to explain several oddities in it’s revolution. When we plot the position of Venus from an Earth centered perspective, Venus reaches the exact same position in the night sky every 8 years. Even more interesting is the fact that if we plot the positions of Venus every day for 8 years, the planet traces out a lovely, 5 petalled rose in the night sky. This association with the rose relates it to all that is feminine, and what better to represent femininity then the Goddess of beauty herself?When we look at Mars, the most striking factor in its appearance is its bright red colour. Instinctively, we associate red with blood, violence and danger. The Romans took this as a sign of impending war from Mars, the god of war, warning them to ready their weapons and armies. Even the two moons of Mars, Phobos and Deimos, are named after his children, who always accompanied their father in battle. Phobos would remind his adversaries of their worst fears and Deimos would terrorize them with horrifying apparitions. In fact, such was their influence that the modern day word “phobia” derives from Phobos.Jupiter, the mightiest god of all, is aptly the biggest planet in our solar system. Even the 4 major satellites of Jupiter, Io, Ganymede, Callisto and Europa, are all beautiful women that Zeus, the Greek form of Jupiter, desired, and were taken by force as his consorts. Again, several anomalies come to mind. As we know, the Romans had no way of knowing the size of the planets, and consequently they shouldn’t have known that Jupiter was the largest planet in the sky. Yet, they named the biggest planet Jupiter, after the king of the gods, the mightiest of gods. Was it a coincidence, or did they somehow know the sizes of the planets?Saturn, the god of time, revolves the slowest around the sun, leisurely taking his time. Saturn is also the god of agriculture and civilization, and is also worshiped as the founder god of the Roman empire. This, along with being the father of Jupiter, was enough to earn him a place among the planets.These are the most important planets in Roman mythology, as the rest of the planets were discovered only after the invention of the telescope. Uranus is an exception in the sense that it is the only planet named after a Greek god, the god of the sky, watching over all of creation from afar.Neptune is named after the god of the sea, possibly due to its watery blue colour. It is important to note that Uranus and Neptune were not named by Romans, as they did not have telescopes. These 2 planets were named by scientists after the discovery of the telescope, in keeping with the rest of the mythological names.Even Pluto was named after the Roman god of the underworld, because of its mysterious nature and other-worldly distance from the sun. In a way, the gods of old still rule over us, dictating the motion of our solar system with their divine powers. The influence of the Planets on the Greeks and Romans was considerate, and largely responsible for the immense expansion of their empires. In a way, their fascination with the planets was understandable, as planets represent something entirely different from our daily lives, and have an aura of mystique and power shrouding them. Even today, the planets are, for me, something that I cannot completely understand, either due to their distance or uncomprehending size. They are always a source of inspiration and wonder for me, and I hope that they will become one for you as well." } , { "title": "Robots Vs Humans For Space Exploration", "url": "http://blog.sedscelestia.org/Robots-vs-Humans-for-Space-Exploration/", "date": "May 4, 2020", "category": "Science Space_News Space_Robotics", "tags": ["Exploration","Robotics","Science","Technology"], "author": "Ashutosh Gupta", "content": "“The Earth is the cradle of humanity, but mankind cannot stay in the cradle forever.”Src: WiredSince the beginning of time, man has been fascinated with the stars and the sky. More and more people are coming up with new ways on how to study the universe. Hence, the more time spent studying space, the more that we will know. Space exploration has allowed us to expand our technology, foster curiosity in humans, discover new worlds, and most importantly push even further to find life on a new planet. Historically, space exploration leaped when the man reached the moon, and it was followed by numerous crewed space missions. On 20 November 1998 history was created when the International Space Station (ISS) launched. From that day forward, ISS has helped immensely in developing our current knowledge of space. Most astronomers will tell you that virtually anything a human can do on another planet, a robot can do, only cheaper and without the risk of losing a life, so lately there has been increased support for sending exclusive robots in space.Why Robots?NASA’s R5 aka ValkyrieRobots are critical for expanding humanity off-planet. They help not just with exploring distant parts of the universe, but also with advancing our economic activity into Earth orbit. A significant advantage of space robots is that they need neither food nor drink and can support very inhospitable conditions. More important still, although expensive to design and produce, their loss is always preferable to that of an astronaut. Sending a robot to space is much cheaper as compared to sending a human. Robots can also do things that would be too risky or impossible for astronauts. They can tirelessly do the same work with accuracy up to nanometers, which is not possible for a human to do in harsh conditions.Economic BenefitHuman spaceflight is extremely expensive. A single flight of the space shuttle costs about $450 million (approx). The shuttle’s cargo bay can carry up to 23,000 kilograms of payload into orbit and can return 14,500 kilograms to Earth. Suppose that if we loaded up the shuttle’s cargo bay with confetti before launching it into space. Even if every kilogram of confetti miraculously turned into a kilogram of gold during the trip, the mission would still lose $80 million (approx). But comparatively, sending a robot in space is way less cheap, and it can function for increased amounts of time as compared to humans. With robots, there is an added benefit of not worrying about the return trip and extra supplies. NASA’s Discovery program has encouraged the design of compact, cost-effective probes that can make precise measurements and transmit high-quality images. Mars Pathfinder, for example, returned a treasure trove of data and pictures for only $265 million.Exploration BenefitTill now the crewed space missions have primarily been concentrated to the moon and Earth’s orbit. For humans to reach further is a very challenging task both in terms of present technology and economically. The most optimistic estimates for a crewed mission to the red planet, range in tens of billions of dollars and could even range up to $1 trillion. In comparison, we have already sent three rovers to Mars including the Pathfinder, traveled to Jupiter and its moons with the help of Galileo spacecraft, and seen hints of a liquid ocean on Europa. In 2004 Cassini probe reached Saturn and the Hubble Space Telescope continually gives us much information about deep space. In past decades, rovers, landers, and orbiters have visited the moon, asteroids, comets, every planet in the solar system, and many of their moons as well. Robotic spacecraft still need human direction, of course, from scientists and engineers in control rooms on Earth.Criticism of human spaceflight comes from many quarters. Some people point to the high cost of human-crewed missions. They contend that NASA has a full slate of tasks to accomplish and that human spaceflight is draining funds from more critical missions. Other critics question the scientific value of sending people into space. They argue that human spaceflight is an expensive “stunt” and that scientific goals can be more easily and satisfactorily accomplished by robotic spacecraft.Why Humans?Astronaut Edwin E. Aldrin Jr., lunar module pilot, poses beside the deployed flag of the United States during the Apollo moon landing, July 20, 1969.REUTERS/NASA/HandoutHumans hold several advantages over robots. They can make quick decisions in response to changing conditions or discoveries, rather than waiting for time-delayed instructions from Earth. They are more mobile than current robot explorers: The Apollo 17 astronauts covered more than 22 miles in three days, a distance that has taken the Mars Opportunity rover eight years to match. Humans can drill for samples deep underground and deploy large-scale geologic instruments, something that no rover has achieved on another body.Instrument InstallationHuman capability is required in space to install and maintain complex scientific instruments and to conduct field exploration. These tasks take advantage of human flexibility, experience, and judgment. They demand skills that are unlikely to be automated within the foreseeable future. A program of purely robotic exploration is inadequate in addressing the critical scientific issues that make the planets worthy of detailed study.Many of the scientific instruments sent into space require careful emplacement and alignment to work correctly. Astronauts have successfully deployed devices in Earth orbit—for example, the Hubble Space Telescope—and on the surface of Earth’s moon. In the case of the space telescope, the repair of the initially flawed instrument and its continued maintenance have been ably accomplished by space shuttle crews on servicing missions. From 1969 to 1972 the Apollo astronauts carefully set up and aligned a variety of experiments on the lunar surface, which provided scientists with a detailed picture of the moon’s interior by measuring seismic activity and heat flow. These experiments operated flawlessly for eight years until shut down in 1977 for financial rather than technical reasons.Scientific OutputIn terms of sheer scientific output, crewed exploration of outer space has a good track record. More than 2,000 papers have been published over the last four decades using data collected during the Apollo missions, and the rate of new articles is still rising. In comparison, the Soviet robotic Luna explorers and NASA’s Mars Exploration rover program – Mars Pathfinder, Spirit, and Opportunity – have each generated around 400 publications. Also, during the Apollo missions, the geologically trained astronauts were able to select the most representative samples of a given locality and to recognize unusual or exotic rocks, and act on such discoveries. In contrast, the Luna samples were scooped up indiscriminately by the robotic probes. We understand the geologic makeup and structure of each Apollo site in much greater detail than those of the Luna sites.ConclusionSome suggested solutions to this problem are making more telepresence robots and giving exclusive control to humans. But a significant challenge for this is the time latency. There is a time latency of 10 minutes between the Earth and Mars, making true telepresence very difficult. Also, no real-time imaging system developed to date can match human vision, which provides 20 times more resolution than a video screen.There are still many challenges in making humans and robots work as partners for space exploration. So we could conclude that the battle between humans and robots for the starring role in the next chapter of space exploration is still unfinished.Header Image Credits: Photo by Science in HD on Unsplash" } , { "title": "What is an Exoplanet?", "url": "http://blog.sedscelestia.org/Exoplanet/", "date": "April 27, 2020", "category": "Uncategorized", "tags": ["Exoplanet","Research"], "author": "Sanika Chepe, Core, SEDS Celestia", "content": "Any planet beyond our solar system is called an exoplanet. They are planets orbiting other stars, similar to how all the planets in the Solar System orbit about the Sun. It is very difficult to see them directly with telescopes as they are hidden by the bright glare of the stars that they orbit. So, the big question here is, how do we detect these planets, which are millions of light-years away from our Solar system, and why are we hunting them in the first place? One of the primary reasons that encouraged astronomers to seek exoplanets is one of the most profound and thought-provoking questions that humanity has ever asked, “Are we alone in the Universe?”. Philosophers and curious humans have been asking this question for thousands of years, but we are the first generation who have the means to answer this question by scientific observations. It is fascinating to know that finding potential life-bearing worlds among the stars is NASA’s next big challenge.How do we look for exoplanets?Exoplanets can be found by using various techniques viz Radial Velocity method, Transit Method, and Direct Imaging. These terms might seem complex however are very simple! Let us take a closer look at each of them.The Radial Velocity method involves looking for “wobbly” stars. We say that planets orbit stars, but that’s not the whole truth. Planets and stars orbit about their mutual centre of mass called Barycentre. These stars appear to be wobbling, due to their off-centre orbit, from a distance. A star’s ‘wobble’ can tell us if a star has planets, how many there are, and how big they are. Wobbling stars are great for finding exoplanets, but how do we see the wobbling stars? The method used is called the Doppler Shift. Energy – sound, radio waves, heat, and light, moves in waves. Have you ever noticed how the sound of an ambulance passing you on the street gets higher in pitch as it gets close to you, and then lower in pitch as it speeds away? The reason is that when an object that emits energy (like an ambulance speaker or a massive, burning star) moves closer to you, the waves bunch up and squish together. And when the object is moving away, the waves stretch out. When visible light waves scrunch together, they look bluer (blueshift) and when visible light waves stretch out, they make an object look more reddish (redshift). Hundreds of planets were discovered using this method in the late ’90s after the European team of Michel Mayor and Didier Queloz announced their discovery of 51 Peg using this method in 1995 (the duo also shared the Nobel prize for physics in 2019!). However, this method was suitable only for detecting bigger planets of size greater than Jupiter compared to smaller planets, like Earth, which created smaller wobbles, which were hard to detect. Finding Earth-sized planets was the subsequent challenge. A space-telescope and a new method then stole the show.The Transit method involves searching for shadows, similar to the phenomenon of a Solar eclipse. When a planet passes directly between its star and an observer, it dims the star’s light by a measurable amount. During a transit, the light curve (a chart of the level of light being observed from the star) shows a dip in brightness. Bigger planets block more light, so they create deeper light curves. Also, the longer a transit event lasts, the farther away that planet is from its star. It can also give us information about the composition of a planet’s atmosphere or its temperature. When an exoplanet passes in front of its star, some of the light passesthrough its atmosphere. Scientists can analyse the colours of this light to get precious clues about its composition. Using this method, they’ve found everything from methane to water vapor on other planets. NASA’s Kepler mission (2009 to 2013) successfully discovered thousands of exoplanets by this amazingly simple method of transit, a few of which even lie in the habitable zone, where life might be possible. We now know that there are thousands of exoplanets out there and NASA’s TESS (Transiting Exoplanet Survey Satellite) launched in April 2018, continues to search for many more in an area 400 times larger than that covered by the Kepler mission!Credits: ESADirect Imaging is a relatively newer method that involves taking pictures of the planets. However, this is quite a task because firstly, they are very far away and secondly, they are millions of times dimmer than the stars they orbit. We are therefore designing instruments to block out the glare of the stars so that we can get a better look at the objects around the stars that might be exoplanets. There are two main methods astronomers use to block the light of a star. One, called Coronography, uses a device inside a telescope to block light from a star before it reaches the telescope’s detector. Coronagraphs are now being used to directly image exoplanets from ground-based observatories. Another method is touse a starshade, a device that’s positioned to block light from a star before it even enters a telescope. For a space-based telescope, a Starshade would be a separate spacecraft, designed to position itself at just the right distance and angle to block the light from the star. Future direct-imaging instruments might be able to take photos of exoplanets that would allow us to identify atmospheric patterns, oceans, and landmasses.Credits: Cornell UniversityOther methods for searching exoplanets include Gravitational microlensing and Astrometry. Gravitational microlensing involves bending and focussing of light from a distant star by gravity as a planet passes between the star and Earth while The underlying principle of Astrometry is, the orbit of a planet can cause a star to wobble around in space about nearby stars in the sky.Src: Wikimedia Commons The above quote truly depicts the curious nature of human beings. The sky has been fascinating humans for ages. Although we face enormous technological challenges in our endeavour of planet-hunting, the forthcoming technological innovations like the James Webb telescope, WFIRST (Wide-Field Infrared Survey Telescope), the Starshade, Coronagraph, etc. bring us closer to finding another ‘pale blue dot’ in this boundless universe.References: https://exoplanets.nasa.gov/what-is-an-exoplanet/about-exoplanets/ https://spaceplace.nasa.gov/all-about-exoplanets/en/Header Image Credits: ESA/Hubble, M. Kornmesser" } , { "title": "The Mythology Of The Zodiac", "url": "http://blog.sedscelestia.org/The-Mythology-of-The-Zodiac/", "date": "April 20, 2020", "category": "Mythology", "tags": ["History","Mythology","Skywatching","Stories","Zodiac"], "author": "Avdhoot Bhandare", "content": "The ZodiacAll of us have heard of the zodiac signs; Taurus, Virgo, Leo, Aries, and many others besides. To understand the origin of these ‘sun’ signs, we first need to know what the ecliptic is. The ecliptic is a huge imaginary circle in the night sky, the path on which the sun travels over the course of a year. It is so-called because eclipses occur when the moon crosses this imaginary line. All the planets except Pluto, and the moon as well, move along the ecliptic.The zodiac constellations are those constellations that the sun passes through over the course of one year. Contrary to popular belief, there are 13 zodiac constellations, but the ancient Babylonians, who started this system, had only 12 months in their calendar and omitted the 13th constellation, Ophiuchus. Each of the 13 constellations has a meaning to its name and is often involved in a fascinating mythical tale of gods, heroes and monsters. Without further ado, let us delve into this plethora of history and knowledge.Aries, the RamPhrixus and Helle were the Twin children of a Boeotian king. The children had a stepmother who hated them and consequently concocted a plan to have them sacrificed to the gods. Just as they were about to be killed, the gods had pity on the children and sent a magical flying ram with golden wool to save them. The ram took them to Colchis, but Helle fell off into the ocean, and that part of the Aegean sea is known as Hellespont, or the sea of Helle in her memory. After reaching Colchis, Phrixus sacrificed the ram to the gods and presented its fleece to the king of Colchis, and this was known as the Golden Fleece, with powerful healing properties which was the quest of Jason and the Argonauts. The ram was immortalized is the night skies by the gods in honor of his sacrifice, and that constellation is now known as Aries, the ram.Zodiac ConstellationsImage: Till Credner (CC BY-SA 4.0)Taurus, the BullZeus, the king of the gods, was never really a faithful husband. He was infatuated with many mortal women, notably beautiful princesses, but, being a married man, had to resort to disguises to seduce them. Zeus once fell in love with Europa, a beautiful princess who loved to play on the beach. He took the form of a beautiful albino bull and swam towards her, and Europa was quickly awed by its beauty. While caressing the horns of the disguised Zeus, he quickly swam out into the open ocean, and Europa had to hold on to his horns to stay afloat. Zeus took her to an island called Crete and seduced her there. One of their children, Minos, became the king of Crete and held bull games in honour of Zeus in the form of Taurus, the Bull.Gemini, the TwinsCastor and Pollux were two twins born to Leda but born of different fathers. Castor’s father was the king of Sparta, while Pollux’s was Zeus. Thus, Pollux was immortal but Castor was not. These twins were the best of friends, sharing many adventures together, and shared a strong bond and a happy life, but it was not meant to be. Such is the curse of immortality that Pollux had to watch his beloved brother die. Distraught, he appealed to his father to bring Castor back, or he would have no will to go on living. Zeus decides to make them both immortal and we see them today as Gemini, the twins, a brotherhood like nothing else.Cancer, the CrabHeracles, the mighty Greek hero was the son of Zeus, a result of one of his extramarital affairs. Consequently, Hera, Zeus’ wife hated him, and to kill him, ordered him to perform 12 deadly tasks. One of these was to kill the mighty and fearsome hydra, a venomous, snake-like creature with many heads. To aid the hydra, Hera sent a crab to bite Heracles’ foot while he was fighting the hydra. Luckily, Heracles managed to focus and smash the crab’s shell with his foot. In recognition for its services, Cancer, the crab was made a constellation by Hera.Leo, the Nemean LionThe Nemean lion was a fearsome, clever beast that preyed on humans. It had a hide that no mortal weapon could pierce, and a razor-sharp array of claws and teeth. It would kidnap the women from a village and lure the warriors to save the damsel in distress, and then ambush and eat them. The first task of Heracles was to kill this monster. Unable to penetrate its hide with his weapons, Heracles ultimately used his prodigious strength to suffocate the lion, and took its hide as a pelt to protect him from all weapons.Virgo, the MaidenVirgo is the goddess of innocence and purity, Astraea. Legend has it that Zeus sent Pandora as a punishment to all mankind. Pandora, a naturally curious young girl, opened a box she was warned not to open, and hence released sickness, envy greed and all sorts of misery on humans. This box was later called Pandora’s box. As a result of these conditions, all the gods left the earth and went to heaven. Astraea, closest to the humans, was the last to leave, and to watch over all of humanity, she took the form of Virgo, the maiden.Libra, the ScalesLibra was actually part of the constellation of Scorpius and formed the claws of the scorpion. However, when Rome was founded, the moon was in the area of sky in which Libra presently is, and the Romans reformed it into the new constellation of Libra, the scales, representing justice, equality and balance, the principles on which Rome was built. In Greek mythology, they represent the scales of Astraea, who was also the goddess of justice, which fell nearby as she ascended to the skies.Scorpio, the ScorpionThe legend of Scorpio is related to Orion, the hunter’s constellation. According to legend, Orion was the greatest mortal hunter the world had ever seen, with skills second only to Artemis, goddess of the hunt. Boasting about the animals he had killed, his claims that he was the greatest hunter of all time reached godly ears. The gods were not at all pleased with his bragging, and sent a monster like no other for him to fight. They created Scorpio, the scorpion to kill Orion. In a bizarre godly twist of events, the hunter was now the hunted, as Orion had never seen scorpions before and did not know how to fight them. He died at the hands (or claws, rather) of Scorpio, and the scorpion has enjoyed a regal place in the night sky, a reward for teaching Orion that, no matter how good you are, there is always someone better.Sagittarius, the CentaurCentaurs are beastial creatures, with the lower bodies of horses, but the head and torso of humans. They are inclined to be violent and riotous, but the Greeks held much more respect for them than others. The centaur Chiron is one of the most famous centaurs in Greek mythology: a learned and talented archer, musician, physician and healer, he also had at his disposal the gift of teaching. He had tutored in his lifetime many of the greatest Greek heroes, including Achilles, Jason and Hercules. He was, however, accidentally shot by Hercules with a poisonous arrow. Not being able to cure himself of the deadly poison, but not being able to die either (he was an immortal being), the gods had pity on his suffering and gave him peace among the stars as Sagittarius, the centaur.Capricornus, the Sea-GoatSea goats were, as the name suggests, animals with the head and body of goats but the lower body and tail of fish. They were, unlike normal goats, very smart and capable of speech, and had the farour of the gods. Pricus was the ancestor of all sea goats and was created by Chronos, the god of time. Pricus was created with the ability to reverse time. As time went by, Pricus realized that his offspring would lie for long hours on the beach, and eventually evolve to lose their hind legs and become normal, mindless land goats. Upset by seeing his children become dumb animals, Pricus reverses time to warn them of their impending doom, forbidding them to ever go near the shore. His children, however, ignore his warnings and continue to visit the shores. Again and again, Pricus would reverse time, and again they would head to shore. Pricus then realizes that he cannot change their destiny, and is immensely saddened by this. He begs Chronos to let him die, but Chronos instead turns him into a constellation high up in the sky, from where he can watch his successors on even the highest mountain tops.Aquarius, the Water CarrierGanymede was the young prince of Troy and was one of the most handsome boys in all of Greece. One day, while roaming in the pasture, he was spotted by Zeus, who was smitten by the boy’s handsome looks. Wanting Ganymede all to himself, Zeus swooped down in the form of a giant eagle and carried the boy off to heaven, and made him his personal slave. All-day long, Ganymede would carry food and wine for Zeus. One day, the boy decided he had enough and poured all the wine and ambrosia onto the earth, and refused to stay the cupbearer of Zeus any longer. Since he had seen the heavens and the gods, the boy could no longer return to the earth but was seen forevermore in the skies, pouring the holy drink of the gods into the night skies.Pisces, the Twin FishDuring the Great War between the gods and the titans, monster Typhon ambushed the gods and threatened to destroy all of them. All the terrified gods transformed into small animals and darted away, except Aphrodite, the goddess of love, and her son Eros, because they had no animal forms. As they were cornered beside a river, two fish agreed to help Aphrodite and Eros escape into the river, as Typhon was a monster of fire and couldn’t enter water. To prevent them from getting lost, the two fish tied their tails together and safely carried the two gods to safety. In recognition of their invaluable help, the constellation of Pisces was made in their honour.The mythology of these constellations, although very fanciful and hardly true, always fascinate me. These stories turn random patterns of unrelated stars in the sky into living, moving characters in a nail-biting story, taking us into the past when chimeras and gorgons roamed the land, and brave, mighty heroes went on conquests to rid the Earth of such hideous creatures. It has led me to read about all the other myths and legends associated with the other constellations, and I hope that all of you will also enjoy the myths and stories as much as I did.Header Image Credits: Photo by Vedrana Filipović on Unsplash" } , { "title": "Evolution Of The First Galaxies", "url": "http://blog.sedscelestia.org/Evolution-of-the-First-Galaxies/", "date": "April 12, 2020", "category": "Messier-Series", "tags": ["Galaxies","Lecture","Matt-Malkan","UCLA"], "author": "Aeishna Khaund", "content": "Lecture by Prof. Matthew A. Malkan, UCLADistinguished professor of Physics and Astronomy at the University of California, Los Angeles, Dr. Matthew Malkan, works to trace the cosmic history of the two primary sources of energy in the Universe: star fusion power and the accretion power of black holes, way back to the Big Bang. His online lecture on April 6, 2020, began with a discussion of our origins, about how we came to be and the role that planets, stars and galaxies had to play in the process. This took us to the topic of the Cosmic Microwave Background and its minute imperfections causing even the slightest over-densities to collapse into the first galaxies. The professor then introduced us to the modern astronomical time machines, the Keck telescopes and showed us some intriguing videos about the unintuitively violent process by which galaxies are formed. Moving on to the detection of these galaxies, the professor explained how surprisingly different captures of the primal galaxies looked as opposed to the galaxies we see today. The last segment talked about the future of galaxy detection, where humongous telescopes would allow us to detect light even from the birth of the universe. Overall, the lecture was a rare insight for students, into the process of observing and analyzing the evolution of the early universe." } , { "title": "CHANDRAYAAN 2- ISRO’s FIRST ‘SOFT-LANDER’", "url": "http://blog.sedscelestia.org/Chandrayaan-2/", "date": "August 12, 2019", "category": "Uncategorized", "tags": ["Science","Space_News"], "author": "Hrutwick Sawant and Aditya K Nair", "content": "ISRO again made Headlines in World News on 22nd July 2019 at 2:43pm IST (09:13 UTC) when Chandrayaan-2, India’s second Lunar Exploration Mission, was launched successfully by GSLV Mk III (Geosynchronous Satellite Launch Vehicle Mark III) at Sathish Dhawan Space Centre in Sriharikota. The launch was initially planned to take place at 2:51am IST on 15th July 2019. But ISRO called off the launch due to a technical snag, which was noticed while filling the cryogenic engine of the rocket.ISRO selected eight scientific instruments for the orbiter, four for the lander, and two for the rover. Chandrayaan-2 will orbit the Earth for 23 days as it says in its new schedule. The satellite would be in the Lunar Transfer Trajectory from day 23 for 8 days. On August 20, it will be embedded into the Moon’s Orbit and will be there till 1st September. On 2nd September, the Vikram lander, inclusive of the Pragyan rover, will be separated from the orbiter and ISRO will be conducting a deboost procedure on 3rd September. The landing will take place on 7th September, the 48th day since launch.Chandrayaan-2 aims to upgrade the scientific objectives of Chandrayaan-1 by way of ‘soft landing’ on the Moon’s surface. Chandrayaan-1 was launched 11 years ago. After a year from its launch, the orbiter suffered from several technical issues such as failure of the star sensors and poor thermal shielding. It stopped sending radio signals about 20:00 UTC on 28th August 2009, shortly after which the ISRO officially declared the mission over. Chandrayaan-1 functioned for 312 days which was intended to be for two years, but the mission achieved 95% of its planned objectives.On 2nd July 2016, NASA used ground-based radar systems to relocate Chandrayaan-1 in its lunar orbit, more than seven years after it was shut down. Over the next three months, repeated observations allowed a precise determination of its orbit which varies between 150 and 270 km in altitude every two years.Chandrayaan-1 carried the Moon Impact Probe (MIP) which was designed to be released from the spacecraft and hit the surface of the moon. On 14th November 2008, the MIP was released and hit the surface near the south pole. The MIP detached itself from Chandrayaan-1 about 100 km from the Moon’s surface and crash-landed near the south pole. All the three instruments, video camera, a radar altimeter, and a mass spectrometer, returned data before the crash.Unlike Chandrayaan-1, its successor plans to accomplish a ‘Soft-landing’. The lander and the rover will land on the near side of the Moon, in the south polar region at a latitude of about 70° south. The Pragyan rover will move on the lunar surface and will do on-site chemical analysis for a period of 14 days (one lunar day). It can relay data to Earth through the help of orbiter and lander. The orbiter will execute its mission for one year in a circularized lunar polar orbit.The main scientific goals of the Chandrayaan-2 mission includes studying the lunar topography, mineralogy, elemental abundance, the exosphere, and signatures of hydroxyl and water ice. The orbiter will map the Moon’s surface which will help in preparing 3D maps. The radar onboard will map the surface and at the same time study the water ice in the south polar region.Chandrayaan-2 is another achievement for ISRO which includes Chandrayaan-1, the Mars orbiter in 2014 (making India the fourth country on the globe and the first Asian country to reach Mars), and Chandrayaan-2, which will be followed by Gaganyaan (India’s first manned mission in 2022)." } , { "title": "Scientists Discover and Confirm the Existence of Two New Dwarf Planets in the Farthest Extremes of the Solar System", "url": "http://blog.sedscelestia.org/Scientists-Confirm-Two-New-Dwarf-Planets/", "date": "May 17, 2019", "category": "Space_News", "tags": ["Dwarf_Planet"], "author": "Avdhoot Bhandare", "content": "The dwarf planets, nicknamed The Goblin and Farout, which are located way beyond Pluto, also hint towards the presence of a far larger body lurking in the depths on the Kuiper belt. Scientists suspect that this large body might be planet X, an elusive and mysterious planet that is thought to exist because it’s presence explains several anomalies in the Solar System.The Goblin2015TG387, more commonly called the Goblin, is a dwarf planet located in the outer Solar System, in the Oort cloud. It’s presence was proposed in 2015 and confirmed recently, on the 2nd of October this year. It’s discovery around Hallowe’en led to its eccentric nickname, and also to the inclusion of the letters ‘TG’ in its official name.Scott Sheppard at Carnegie Institution for Science, Chad Trujillo at Northern Arizona University and David Tholen at the University of Hawaii announced the finding on October 2, 2018. They found it during an intensive search for Planet X, a search these astronomers said was “the deepest and most comprehensive survey of its kind so far”.The planet is what scientists call an Inner Oort Cloud Object (IOCO), meaning that it is isolated from most of the mass of the solar system and hence extremely interesting to study. They can act as probes to understand what happens on the icy edges of our Solar System. Many other such IOCOs exist, like Sedna, 2012VP113, etc. The Goblin is an extremely interesting object to study. It lies around 80 AU away from the sun (one AU, or Astronomical Unit, is the distance between the Sun and the Earth), which is far. In comparision, Pluto is around 34 AU, so this planet is more than twice as far away as Pluto, and that’s when its close by. At its aphelion, its a massive 2,300 AU away! Its a small, dark, and lonely world, only about 300km in diameter. However, what makes it more interesting is the tantalizing hints it keeps dropping, pertaining to the existence of the mysterious planet X.An artist’s impression of The GoblinCredits: Carnegie Institution for Science,DTM: Roberto Molar Candanosa/Scott SheppardInterestingly, all these IOCOs, like our little goblin, Sedna and 2012VP113, have suspiciously similar perhelions. This could be explained by a large body ‘pushing’ them into similar orbits. To test this theory, scientists carried out different simulations by placing different sized bodies in orbit around the sun and seeing how their gravitational field affects our IOCOs. The results turned out to be in favour of Planet X, i.e. it kept the orbit of the goblin stable by ‘shepherding’ it, similar to how Saturn’s moons shepherd its rings.Of course, none of this is conclusive proof of the existence of a mysterious, super-Earth sized planet in the far reaches of our Solar System, but it certainly does point to the possibility that it could exist, and that, along with other evidence, gives scientists more than enough incentive to keep looking.What is Planet X?Planet X is a hypothetical planet thought to exist beyond Pluto. Search for this elusive planet has been on since the late 1800s, and was thought to have been discovered when Pluto was found. However, scientists realised that Pluto was too small to cause the significant changes in the orbits of certain objects which resumed the search for the new planet, fueled by conspiracy theories about the Nibiru cataclysm.Scientists realised that the orbits of several objects in and beyond the Kuiper belt, like the goblin, Sedna, 2012VP113, and 2 others have very similar perhelions, which cause them to cluster together, even though they have no outwardly visible reason to do so. The theory is that an as yet undiscovered rocky, icy planet exists in the Kuiper belt, way beyond Pluto that affects the revolution of these bodies and clusters them together with its gravity.The mysterious planet X.Src:Getty imagesJudging from its gravitational influence, it has a mass of about 10 times that of earth, and an orbit of about 20 times that of Neptune. This means that it would take the planet a stunning 10,000 years to orbit the sun, which might explain why we haven’t discovered it yet. The astronomical community, however, is highly sceptical about its existence. There isn’t much conclusive evidence about its presence, apart from its effect on several other astronomical bodies. This scepticism is fueled by the Nibiru conspiracy, which predicted that a planet from the outer depths of the Solar System would come and crash into the Earth, changing its orbit and obliterating all life on Earth. The date, provided by several conspiracy buffs as somewhere in September of 2017, was conveniently postponed when no such planet came careening into the Solar System.What the Nibiru Cataclysm might look like if it actually happened.Credits: Lynette CookThe determination of scientists knows no bounds, and hence they keep looking for it. Because of its size, scientists calculate that its visible, and hence now they will start looking with the strongest telescopes possible inspite of slim chances of success, because, frankly, discovering a whole new planet is quite extraordinary and exciting, to say the least!FaroutThe search for planet X yielded another interesting object; a pink, glowing orb lurking way beyond Pluto. This object, now a confirmed dwarf planet, moved so slowly, and hence, is so far, that the first word the lead of the project, Scott Sheppard, said was “farout”. And it stuck. The pink little dwarf, officially called 2018 VG18, was fondly named “Farout”. Many amazing facts describe our pink friend. Firstly, because it moves at a horrendously slow pace, it has to be really, really far away. Later analysis confirmed that it is, in fact, the farthest object ever to be seen in our Solar System. It is 120 AU away, while Pluto, former planet, was our benchmark for being far away, is a mere 34 AU away from the sun. To be so far away and yet be visible, means it has to be fairly large in size, and it is, having a diameter of 500-600 km.Farout, the lonely little pink planet.The second weird fact is that it is pink, which is a very interesting fact. Not many objects in our Solar System are pink. This pink colour can have many reasons, ranging from a different type of gas, some new sort of sandy material to an alien invasion by a Barbie-like race. The real explanation, however, is far less dramatic. The rosy hue is mostly formed due to ice that has been irradiated by the sun over millions of years, but we all have our fingers crossed for the alien invasion.Because its so slow, scientists have had difficulty in mapping out its orbit, which they hope will give more evidence to the existence of planet X. Just like the other dwarf planets, if our pink orb also has a perhelion that coincides with the others, it would strongly suggest that planet X does exist and is really playing a hide and seek game of astronomical proportions.Header Image Credits: Illustration by Roberto Molar Candanosa is courtesy of the Carnegie Institution for Science" } , { "title": "Cosmic ray accelerator through the eye of Multi Messenger Astrophysics", "url": "http://blog.sedscelestia.org/Cosmic-Ray-Accelerator/", "date": "March 9, 2019", "category": "Uncategorized", "tags": ["Science","Space_News"], "author": "Anonymous", "content": "Blazar , Cosmic ray acceleratorSource: IceCube, WIPACThe main idea of Multi-messenger astronomy is to search for sources of cosmic rays byobserving high energy gamma rays and neutrinos from a region of the sky/universe whereprotons are accelerated to high energies. Astrophysical Multimessenger Observatory network is one such network making MultiMessenger astrophysics possible.Chargeless, weakly-interacting and low mass neutrinos are the ideal astronomical messengers of powerful sources like cosmic ray accelerators, sun and supernovae.They are not deflected, scattered, absorbed by galactic and extra-galactic magnetic fields, radiation fields and dust. But this nature of the interaction of neutrinos make them difficult to bobserved. It was found that to detect one neutrino of PeV energy per year requires 1sq.km size neutrino observatory, which is the design principle of IceCube 1 . As the neutrino flux spectrum falls off according to a power law with spectral index ’2’ for cosmogenic neutrinos and ’3’ for atmospheric neutrinos, one can observe the high energy extragalactic astrophysical neutrinos.We believe in the rationale that the gravitational energy released near neutron stars and BH (black holes), power the acceleration of protons through shock wave or Fermi first order acceleration. This acceleration subsequently produces high energy neutrinos through various interactions at various epochs like: in their source during acceleration (jet active AGN), in the source environment after the release and while propagating through universal background radiation (EBL). 2In Astroparticle physics, especially in research areas of neutrino producing sites- blazars, we work in the framework of photo-hadronic one zone emission model (proton-gamma interaction). We also make the following assumptions that neutrinos have zero rest mass (which can be justified on the basis of energy scales involved in our studies) and that cosmic rays mainly consists of protons. So far, we have only observed a diffused flux of neutrinos rather than apoint source at IceCube. In interactions of cosmic ray protons with the background radiation, further secondary particles like pionic photons, electron & muon neutrinos, and matter and anti-matter pairs are produced. Take note that IceCube does not differentiate between anti-neutrinos and neutrinos. After neutrino oscillations, the averaged composition of neutrino flavor observed at the detector in terms of νe: νμ: ντ is 1:1:1, instead of 1:2:0 as they are whenproduced. 3IceCube Neutrino Observatory, South Pole StationSource: IceCube , WIPACIceCube Neutrino Observatory, Inside the IceSource: SciencemagThese high energy neutrinos interact via Charged current(CC) and Neutral Current(NC) interactions to produce further secondary charged particles which travel faster than light in that medium to produce Cherenkov radiation. These secondary charged particles are observed in DOMs of IceCube in either, ’tracks’ or ’cascades’ type of event, based on type of neutrino. Based on the collected data through PMTs, one can reconstruct the energy, flavor, and directionof the incident neutrino.Charged current and Neutral Current interactionSource: HEPTracks and CascadesSource: IceCube, WIPACDOM (Digital Optical Module)Source: IceCube, WIPACActive Galactic Nuclei (AGN) has been considered as the source population of the observed high energy cosmic rays at Earth. They follow Hillas Criteria : E max ≤ ZecBR, where R is the gyro-radius. They also satisfy the energetically requirements to accelerate the particles like electrons, protons and other heavy nuclei to such high energies. These particles may have been produced in generic fireballs and supernova too but our focus will be mainly on the regions injets of AGN.Blazars are extremely compact AGN with jet directly pointing in the direction of Earth. They are the brightest sources of high energy gamma rays and also can be the source of high energy diffuse flux high energy astrophysical neutrinos observed at IceCube. These usually have a double hump structure in the gamma-ray spectrum due to synchrotron and inverse Compton scattering. Blobs are huge structures in the jets of AGN where the acceleration of protons and production of neutrinos can happen. Protons can interact with the following to produce highenergy neutrinos : 4 Synchrotron radiation Photons from the accretion disk Dense dust clouds near AGN Broadline emission clouds(BLR)Credits: CoolWiki CaltechIn 2017, an IceCube event, ‘IC172209A’, a high energy neutrino had been detected to be in containment region of BL Lac object TXS0506+056 Blazar. During the same time a rise in the flux of spectrum of gamma rays was observed from the same region, opening to a new era of multi-messenger astrophysics. Motivated by this, IceCube conducted a search in its archival data to find a high flux during the period of 110 days from Sept to Dec 2014 . 5Usually, the environment of jetted active AGN, mainly jet power and target photon field spectrum are constrained by first reconstructing a minimum target photon field required to produce observed neutrino spectrum computationally and then by comparing the comprehensive study of cascade spectrum emerging from the source with the MWL(Multi wavelength) data. During the 110 day flare period in 2014 physicists used Quasi-simultaneous MWL data in Optical g and V band, X-rays and Gamma-ray spectrum from ASAS-SN, BAT, and Fermi-LAT respectively.After doing the above analysis, physicists have come to the conclusion that neutrinos and bulk of gamma rays observed from the direction of TXS0506+056 cannot have been initiated by the same process and may not be from the region of AGN. Physicists hypothesize that maybe co-acceleration of electrons and protons can be expected to provide a causal connection between photon and neutrino production. It is observed that the same target photon field for an efficient neutrino production is opaque to high energy GeV gamma-ray photons. It is also observed that gamma-ray flux strictly associated with neutrino flare lies significantly below the GeV-flux detected contemporaneously to the neutrino flare in 2014. 6BL Lac type Blazar, off the left shoulder of the OrionSource: Fermi-LATThe main problems in concluding an exact source and its mechanism as the origin of cosmic rays are the absence of real-time Multi-messenger data and point sources. But recently a network called AMON has been set up to achieve this goal. In addition, for the first time IceCube might have found a point source instead of a diffuse flux of particles, which will be released soon!GLOSSARY amon.psu.edu - AMON astronomy.ohio-state.edu - ASAN-SN wikipedia.org - BL Lac Object wikipedia.org - Cherenkov radiation fermi.gsfc.nasa.gov - Fermi-LAT wikipedia.org - IceCube wikipedia.org - Neutrinos wikipedia.org - Neutrino Oscillation wikipedia.org - Pion swift.gsfc.nasa.gov - Swift-BATREFERENCES IceCube Preliminary Design Document ↩ High-energy Neutrino Astronomy: The Cosmic Ray Connection ↩ Astroparticle Physics with High Energy Neutrinos: from AMANDA to IceCube ↩ Blazar Flares as an Origin of High-Energy Cosmic Neutrinos? ↩ On the Neutrino Flares from the Direction of TXS 0506+056 ↩ Cascading Constraints from Neutrino Emitting Blazars: The case of TXS 0506+056 ↩ " } , { "title": "Why we don’t have a moon base, and other future predictions", "url": "http://blog.sedscelestia.org/Why-no-moon-base/", "date": "January 22, 2019", "category": "Uncategorized", "tags": ["Science","Space_News","Robots","Moon_base"], "author": "Anonymous", "content": "In 1968, at the height of the Space Race, Stanley Kubrick released a film that would go on to be called one of Hollywood’s greatest. This film depicted commercial travel to space, a moon base, videophones, and the famous supercomputer HAL 9000. This film was 2001: A Space Odyssey, and it made bold predictions about the future of humanity.In the film, Back to the Future 2, 2015 is shown to be a modern place with fast legal systems, advanced communication technologies, flying cars and clean fuel. This too seems far-fetched today.The year 2018 is ending, and watching this film makes one wonder: where is everything these films show? How did humanities technological leaps stop short so suddenly? This films are emblematic of the vision of a generation of people living in nearly endless prosperity, growth and technological advancement. Within 20 years the world had come from launching its first satellite to landing on the moon. They had witnessed the birth and growth of commercial computers and modern antibiotics. This generation felt that the progress would only grow, as bigger and better things would keep coming.WHERE IS THE MOON BASE?The glories of the 1960s and 70s were at a high cost, and things did not always go the way most people thought they would. Even just after Neil Armstrong’s historic landing on the moon, only 52% of the US population believed the endeavor was worth it. NASA had been allocated 14% of the entire federal budget at that time to make this happen. Not only that, these projects were prime targets for populists to target. While we do not have a moon base today, it is only because the world decided to come together to accomplish things like a common International Space Station, which, many would argue, is a better thing than a national moon base.Also, while NASA saw budget cuts and an American population that just was not that interested in science anymore, other countries like China and India are stepping up their efforts to surpass NASA’s legacy. Moreover, how can we forget this guy?WHERE IS THE NEXT BIG THEORY?Truth be told, most people do not understand the quantum theory at all. Even scientists do not know what is going on sometimes, and it’s not their fault. The problem is not that Sheldon Cooper said something that nobody else could ever understand, but that the theory itself. is too far ahead of its time. It is extremely costly to do experiments to confirm high energy phenomena and discover subatomic structures. A lot of the theory cannot be tested until the technologies are developed.This is what makes science such a long drawn out process.The hard sciences are mostly figured out now, and unfortunately, they are not given the kind of attention that they used to get anymore. But there are continuous advancements in interdisciplinary fields: look at graphene, nanoparticles, solar sails and efficiency advancements for energy sources.These developments deserve just as much attention as the theory of relatively once got, but they are too specialized to have everyone understand their significance.WHERE IS MY OWN SUPERCOMPUTER?You’re using it.An Apple Watch can be made to run Windows 95.This miniaturization is accompanied by an increase in output. We have developed technologies that let us mass produce with accuracies going down to the size of a few atoms! While most people expect supercomputers to be something likeThey have become more likeYour computers can do amazing things, as you can see when you play demanding games on it. A supercomputer is designed to be better than everything else out there. But that does not mean your mobile phone can never catch up.WHERE IS MY C3PO?Yeah, robots can do amazing things now. But instead of looking forThey might look likeAndActual robots are pretty advanced, but as it turns out, making them human is sometimes useless. Your car with an autopilot integrated into can have better visual than a robot driver, and also spare a seat for you. Your intelligent garden bot can cut grass faster and it takes less space in the shed.“But hey”, you would say, “you did not build any humanoid then?”Well, we did.This robot is now a citizen of Saudi Arabia. However, making robots like her is incredibly expensive, and it would be a foolish waste of resources to get a robot just to put the shoes back in the rack.OKAY, OKAY, SO WHAT ABOUT THE FLYING CARS? THE CLEAN FUEL?We have clean fuel and is getting cleaner. There is a ton of research and government support for them. Petroleum-based cars would probably be illegal in many countries by 2050. We already have Tesla as one of the leading manufacturers of cars in the US. Our energy comes from hydropower, nuclear and solar more so than before. Coal plants are on their way out.And flying cars were never practical. It takes too much energy to get them up, and the regulations would be tough to work with. The awesomeness dissolves once you realize the implications of an accident mid-flight. Moreover, imagine this: 10 cars hovering bumper to bumper because of a red light or just to let birds get by. The air pressure in the area drops because of their combined thrust, and all of them fall to the ground together, injuring and possibly killing someone. Too dark for lawmakers to allow these flights to happen, right?SO, WHAT DID THE MOVIES GET RIGHT? VIDEO CALLS?Not just video calls, a lot of things. There is a space station. There is a lot of reconnaissance of exoplanets and the solar system. Enterprising people look set to surpass the wildest imaginations of those generations: they might capture an asteroid and mine them for resources. We have ultrafast internet; a lot of diseases are mostly eradicated save for some lawless areas, and the rest might be cured by 2050 and even eradicated by the end of the century.These movies (at least the well-made ones that stay in public memory after decades and therefore can be called to have a vision other than to make money) signify the aspirations of its time, and what its people expect the world to be. It is for us to make some more predictions so that someone forty years from now can read these articles, watch The Martian, and realize just how much effort humans put into rescuing Matt Damon from wherever he seems to end up.Bye." } , { "title": "Scientists Discover Pairs Of Merging Supermassive Black Holes", "url": "http://blog.sedscelestia.org/Scientists-Discover-Pairs-of-Merging-Supermassive-Black-Holes/", "date": "December 22, 2018", "category": "Uncategorized", "tags": ["Black_Holes"], "author": "Anonymous", "content": "The study, which was conducted for more than 450 merging galaxies, has managed to observe multiple pairs of black holes in their final stage of mergers.Led by University of Maryland alumnus Michael Koss, a research scientist at Eureka Scientific, Inc., with contributions from UMD astronomers, the team surveyed hundreds of nearby galaxies using data from multiple observatories and telescopes. The team used 10 years’ worth of data from the Burst Alert Telescope (BAT) aboard NASA’s Neil Gehrels Swift Observatory to shortlist their galaxies, and then sifted through 20 years’ worth of Hubble images to observe the galaxies, finally using the W.M. Keck Observatory in Hawaii to get sharper, clearer images of the mergers. This process, while quite arduous and painstaking, was quite effective and yielded crisp and clear results.WHY ARE MERGING BLACK HOLES SO DIFFICULT TO OBSERVE?The black holes which were the subject of this research are the ones usually found at the center of galaxies; massive, and surrounded by a huge cloud of dust, and innumerable stars. They only have the chance to merge when their galaxies are close enough to merge, i.e., black holes merge when their galaxies merge.Observing these black holes is difficult for several reasons. Firstly, when galaxies are locked in gravitational battle, they spew out huge clouds of dust and gas, which obscure the center of the merging galaxies. These clouds allow barely any visible light to pass through. Secondly, the merging of galaxies takes billions of years, while the coalescence of the black holes happens in a few million years; hence we are left with quite a small time period (on galactic terms) to observe them just before and during their merger. These 2 things present quite the predicament when trying to catch these black holes in their merging moments.HOW DID THE TEAM OVERCOME THESE PROBLEMS?Since the clouds covered the center of the galaxies, using visible light was not an option. The team had to resort to the use of x-rays and infrared light. Firstly, they reasoned that colliding galaxies would release bursts of x-rays, and such bursts would be noticed and recorded by an instrument called the Burst Alert Telescope (BAT). Meticulous examination of the past 10 years’ records of this machine yielded a list of potential colliding galaxies. The scientists then turned to Hubble’s records for confirmation of the source, as many astronomical events other than galactic collisions release bursts of x-rays. The team then had to comb through 20 years of records to finally obtain their list of galaxies. However, to their dismay, they discovered that the images from Hubble were not clear enough, as they were in the visible spectrum. As a remedy to this, the team used the W.M. Keck Observatory in Hawaii to get their images. The speciality of this observatory is that it can take images in the infrared and near-infrared region, and they photographed 96 of the 481 galaxies in this way. This method bore good fruit, and yielded sharp, crystal clear images.The team targeted galaxies located at an average of 330 million light-years from Earth — relatively close by in cosmic terms. Many of the galaxies are similar in size to the Milky Way and Andromeda galaxies. In total, they analyzed 96 galaxies observed with the Keck telescope and 385 galaxies from the Hubble archive. The scope of their research, and their clever use of x-rays, knowing that they would break through the cocoon of dust, is what sets this research apart from previous attempts.WHAT HAPPENS WHEN THE BLACK HOLES FINALLY MERGE TOGETHER?The conjoining of galaxies takes billions of years; hence the mergers of black holes is also quite a lengthy process. In comparision to the time it takes the galaxies to come together, the coalescence of the black holes themselves is a short event, taking perhaps 10 or 15 million years. It is essential to observe the black holes in this elusive stage, and the team has managed to do just that. Out of all the galaxies they observed, about 17% of them had a pair of black holes at their center, slowly spiraling towards each other in a train wreck of astronomical proportions. But what happens when they finally merge into a monstrous, ultra massive black hole? In the coming 10 million years, most of these black holes will complete their celestial dance and become a single, huge entity, releasing massive amounts of energy in the form of gravitational waves. These waves can be studied by LIGO, the Laser Interferometer Gravitational-Wave Observatory which is built for that very purpose. Scientists hope to gather large amounts of information from these events.WHAT HAVE WE LEARNT FROM THIS RESEARCH?This research paper has answered many of the questions that had scientists scratching their heads for quite a while, the most important of them being the origin of supermassive black holes. For a black hole to become bigger, it has to keep eating huge amounts of matter, which scientists previously thought came from the gas and dust surrounding them at the center of their galaxies. However, this study has pointed out that these black holes can be formed during the coalescence of galaxies as well. It also gives us some insight into the fate of our galaxy, which is on a collision course with the nearby Andromeda galaxy. These galaxies will merge over the course of a few billion years in a violent and spectacular fashion, forming a bigger galaxy, and an even bigger black hole.WHAT ARE THE FUTURE PROSPECTS OF THIS RESEARCH?Future infrared telescopes, such as NASA’s highly anticipated James Webb Space Telescope (JWST) will provide even better views of the dusty, obscured centers of merging galaxies. It may even reveal information that was too subtle for the Hubble space telescope to pick up, as, in some cases, Hubble cannot resolve the two nuclei and they just appear as one. JWST will also be able to measure the masses, growth rates and other physical parameters for each black hole. Also, the work-in-progress Laser Interferometer Space Antenna (LISA) is another instrument made to measure gravitational waves, which will help in further studying any currently merging black holes." } , { "title": "One Of The Oldest Stars In The Universe Discovered", "url": "http://blog.sedscelestia.org/One-of-the-Oldest-Stars-in-the-Universe-Discovered/", "date": "November 15, 2018", "category": "Science Space_News", "tags": ["Oldest_Star","Red_Dwarf"], "author": "Avdhoot Bhandare", "content": "“The small red dwarf, which is estimated to be 13.5 billion years old, is, surprisingly, a part of the Milky Way itself”.Johns Hopkins University in Baltimore, Maryland made this startling announcement on November the 5th, based on observations made using the Magellan Clay Telescope at Las Campanas Observatory in Chile and the Gemini Observatories in Chile and Hawaii. The star’s age, which is thought to be 13.5 billion years old, was estimated by studying the heavy metal content of the star.How does the amount of metal in a star decide its age?The earliest stars in the Universe were formed mostly from Hydrogen and Helium, and traces of Lithium. That is because, when the Universe was formed, these were the only elements in existence. As stars burned away, metals were formed inside their cores, and these metals were eventually added to the star-forming primordial soup when the stars exploded as supernovae. Over the generations, the amount of metal inside the stars increased due to this process. From this, scientists infer that the oldest stars had barely any metal content inside them. Another factor is the type of metal; heavier metals were formed later on, and hence heavier metals are found in younger stars.How do scientists find the amount of metal inside a star?Scientists can identify the type of metals in a star by studying the spectrum of light from the star: each element has a certain characteristic wavelength associated with it. The presence or absence of these wavelengths, indicated by bright or dark bands in the spectrum, can tell scientists about the composition of the stars.More about our special starThe star, called 2MASS J18082002-5104378 B, was discovered quite accidentally. Kevin Schlaufman, the lead author of the paper, and his team were analyzing a much bigger star for its composition. It was then that they noticed that the star had a slight wobble to its spin; the team concluded that it might be part of a system of stars. It was then that our star was discovered. Analysis of its spectrum showed hardly any metal content. Schlaufman said in a statement, “This star is maybe one in 10 million.”The star has several interesting features. Firstly, the star is estimated to be 13.5 billion years old, which means that the star was formed a mere 200 million years after the Big Bang, which was thought to have occurred 13.7 billion years ago. Secondly, it’s located in the Milky Way itself, about 2,000 light-years away. This has led scientists to reconsider the age of our galaxy, which they now think might be 3 billion years older than previously thought. Thirdly, it has only about 14% the mass of the sun and has a metal content equal to the mass of the planet Mercury. In comparison, our sun, which comes about a 1,000 generations after the Big Bang, has metal content equal to about 14 Jupiters. The previous record-holder star had metal content equal to the mass of Mars.Exciting new possibilitiesScientists have learnt a lot from this discovery, and hope that they can learn much more about the formation of the earliest star systems, and also the composition of the Universe after the Big Bang. The fact the the star is so tiny has changed the idea about the earliest stars. Since there was mostly hydrogen gas in the Universe after the Big Bang, and hydrogen is a poor coolant, the stars were much hotter and turbulent, and consequently needed much more gravity, and hence mass, to keep them together. The stars thus formed were massive, hot, and burnt out their violent lives quickly, ending in spectacular supernovae. This is one of the reasons that older stars are so rare; they had much shorter lifespans. The discovery of 2MASS J18082002-5104378 B, however, has changed that theory, implying that smaller stars could have formed as well. Because the star is so small, it spends its fuel at a comparatively slower rate, and can live for much longer. It can potentially live for a trillion years.The discovery of this star has opened up new avenues to information about the early Universe; the composition after the Big Bang, and the processes of star formation. We have also learned that the Milky Way is older than we thought, by about 3 billion years. Scientists hope that we can learn much more from the discoveries of these elusive, ‘first generation’ stars." } , { "title": "Principles In Theoretical Physics And Holographic Principle", "url": "http://blog.sedscelestia.org/Principles-in-Theoretical-Physics-And-Holographic-Principle/", "date": "September 17, 2018", "category": "Uncategorized", "tags": ["Theoretical_Physics","Holographic","Physics"], "author": "Anonymous", "content": "The Holographic principle was first proposed by physicist Leonard Susskind in the 1990s. He showed that many of the laws of physics can be described mathematically using two dimensions, rather than the three we experience. Cosmologists like this approach because it could help solve one of the biggest puzzles in physics: how gravity works on extremely small scales. Without this, physicists struggle to understand what happens inside a black hole, or what happened at the moment the universe came into existence.In short, the holographic principle amounts to the following two postulates: A gravitational theory describing a region of space is equivalent to a theory defined only on the surface area that encloses the region. The boundary of a region of space contains at most one piece of information per square Planck length.DEGREES OF FREEDOMThe number of independent ways in which a system may possess translational, vibrational or rotational motion or in other words the number of independent ways in which a dynamic system can move and exist, without violating any constraint imposed on it, is termed as number of degrees of freedom for that system.For our purpose, let us restrict the system to a finite region of volume V and boundary area A. It is assumed that system exists in a region of weak gravity and asymptotic flat space so that the above definition is not blurred due to general relativistic effects. From motivations of Information theory, associated Hartley’s analysis and micro-canonical ensemble theory of statistical mechanics, one can try to define the number of degrees of freedom ,N,for a quantum mechanical system having Hilbert space H, as,\\[N =ln(n)= lndimH\\]For a harmonic oscillator , \\(N → ∞\\) . Here one can also try to define N in terms of number of bits of information(\\(1bit = ln(2)\\)). Suppose we have a system of 10 spins which can take 2 independent values, then \\(n = 2^{10}\\)\\[N = 10 ln2 or N =10 bits.\\]PRINCIPLEFundamental theories in physics, in general, have been formulated and modified based on recognition of new principles emerging from some keen observations of things happening around us and through various thought experiments and processes involving different conditions.Principle, in some sense, can be considered as the fundamental assumption in a theory, the ultimate and innermost layer in our understanding of the universe around us.A principle must be incorporated into laws of physics or to put it in another way, the laws of physics should be based on or formulated around the principle.Principles can originate when there is a inconsistency between two fundamental theories about nature. For example, the principle of relativity and upper limit of the speed at which information can be exchanged between two events has been incorporated into special theory of relativity by Albert Einstein. This incorporation supports Maxwell’s laws of electrodynamics and opposes Galilean relativity, leading to many new realizations like length contractions and time dilation.Similarly, a principle may originate from recognizing new symmetry or pattern in nature. The new principle may force new theories to incorporate this pattern into the existing laws. For example, based on the principle of equivalence that existed in Newtonian gravity ,the proportionality between inertial mass and gravitational mass had to be incorporated into Einstein’s general relativity, though the principle changed a little while being taken into consideration.Holographic principle belongs to the later class. It forces systems present in certain spacetime and associated geometry to have a precise and general bound to the information content, entropy or number of degrees of freedom. This principle strictly states that its origin must be found in some theory of spacetime and matter like the quantum theory of gravity.But, to some extent, this principle seems to belong to the earlier class too. There is a contradiction between the number of degrees of freedom predicted by local field theory where it depends on the volume of the system and spherical entropy bound as per which the number of degrees of freedom is dependent on the area of the bounded region.Holographic principle drastically reduces the degrees of freedom present in local field theory. It tries to employ Quantum mechanical Unitarity, a restriction on the allowed evolution of quantum systems that ensures the sum of probabilities of all possible outcomes of any event equals 1.In general, the information can be encoded in many ways. Though Holographic principle tells us about the number of degrees of freedom , it does not talk about the nature of information. It can be inferred that some abstract and pure information may underlie beneath all the physics which is making new concrete models tough to accept the Holographic principle.GLOSSARYInformation theory: A branch of mathematics that overlaps into communications engineering, biology, medical science, sociology, and psychology. It is devoted to the discovery and exploration of mathematical laws that govern the behavior of data as it is transferred, stored, or retrieved.Micro-canonical ensemble theory An ensemble that is used to represent the possible states of a mechanical system which has an exactly specified total energy.Hilbert Space: A vector space equipped with an inner product, which can be thought of as a generalization of the dot product in Euclidean space, with the additional property that the metric coming from the inner product makes the vector space into a complete metric space.Asymptotic flat space: A Lorentzian manifold in which, roughly speaking, the curvature vanishes at large distances from some region." } , { "title": "Synchronization And Chimera States", "url": "http://blog.sedscelestia.org/Synchronization-and-Chimera-States/", "date": "June 11, 2018", "category": "Uncategorized", "tags": ["Science"], "author": "Anonymous", "content": "Synchronization is a process where two or more individual systems interacting with each other move together in terms of their dynamics. In the 60s of XVII century the longitude problem, i.e., finding a robust, accurate method of the longitude determination for marine navigation was an outstanding challenge. Huygens believed that pendulum clocks, suitably modified to withstand the rigors of the sea, could be sufficiently accurate to reliably determine the longitude. He performed an experiment which showed the tendency of two pendula to synchronize, or anti-synchronize when mounted together on the same beam. Two pendula, mounted together, always ended up swinging in exactly opposite directions, regardless of their respective individual motion. Huygens originally believed that synchronization occured due to air currents shared between two pendula, but after performing several simple tests he dismissed this and attributed the sympathetic motion of pendula to imperceptible movement in the beam from which both pendula were suspended.Other examples where synchronization is observed are fireflies, population of cicada species, pacemaker cells, clapping among audience, voltage in Josephson junction, neutrino oscillations in early universe and a lot more physical and biological systems. There are many types of synchronizations but primarily they can be classified into ’In-phase’ and ’Anti-phase’ synchronizations. Flow on a circle and models like uniform and non-uniform oscillators can be used to study and understand how synchronization arises in systems like fireflies and Josephson junction.In synchronization, the final dynamics usually depend on external parameters and type of coupling. They also depend on similarities of oscillators involved where complete synchrony can be obtained only when all the oscillators are identical but if they are not, they will be phase locked with some steady and stable frequency ratio. In this phenomenon, oscillators always try to catch up with the other ones by either increasing or decreasing their frequencies, thus affecting the current next phase dynamics of the oscillators.One of the famous systems used to model dynamics of a population of oscillators is Kuramoto model. It has sinusoidal type of coupling in its oscillators in a given network.The model makes certain basic assumptions like weak coupling and oscillators being identical or nearly identical.There is an interesting phenomenon observed in synchronization called ‘Chimera states‘. Chimera or also known as spatio-temporal dynamics is a phenomenon having coexistence of both synchrony and asynchrony in a given population of oscillators coupled to each other. It can also be seen as spatial coexistence of coherent and incoherent oscillators. Unlike partial asynchrony observed in a system where synchronization is taking place, these chimera states are stable.Until Kuramoto and his colleagues made observations on synchronization while trying to simulate the dynamics of Ginzburg-Landau equation(a modulation that describes the evolution of small perturbations of a marginally unstable basic state of a system of nonlinear partial differential equations on an unbounded domain), mathematicians and physicists thought synchrony and disorder are mutually exclusive for a given system. Later on, many people including Strogatz found that both synchrony and disorder can arise simultaneously in a given population of identical oscillators given that the coupling is non local(the coupling strength decreases with respect to the distance between oscillators). It was also observed that no fine tuning of initial conditions or specific cases are required to get chimera behaviour.Chimera states were observed in neuronal models, chaotic systems, complex networks, time varying networks, modular types and Hopf normal forms. Recently, they have been observed numerically in systems with topology of global, local and one way coupling too. Experimental evidence of these have been observed in optical coupled maps, coupled chemical oscillators, metronomes and squid meta-materials. Application of chimera can be seen in brain diseases like Parkinson’s, epileptic seizures, Alzheimer’s, brain tumors and also in slow wave sleep of some aquatic animals and migrated birds where half part of the brain is active and the other half is in sleep.Header Image Credits: Photo by Radim Schreiber." } , { "title": "Thermodyanmics of Black Holes", "url": "http://blog.sedscelestia.org/Thermodynamics-of-Black-Holes/", "date": "March 31, 2018", "category": "Uncategorized", "tags": ["Black_holes","Hawking","Thermodynamics"], "author": "Anonymous", "content": "From the instant we found out about these mysterious objects in our universe – the black holes- we have been reviewing all sorts of physics that are valid for it, whether they sustain or break down. One such aspect that late physicist Prof. Stephen Hawking studied along with Jacob Bekenstein was whether thermodynamics, the science that governs everything ranging from micro-level atomic particles to astronomical level objects, be applied to such a weird creation. But the main problem was that we didn’t know anything about it at all! Starting from the facts known about its origin and nature and making some assumptions, they made a new field called black hole thermodynamics.The assumptions made arose from the very nature of laws of thermodynamics. The second law of thermodynamics states that for an isolated system (i.e. no exchange of matter or energy with the surrounding) the total entropy can never decrease. This implies that black holes should have some entropy because otherwise, we can violate the law by throwing some mass in it and decreasing the total entropy of the universe. Using elementary thermodynamics, some previously derived theorems about black holes by Hawking, Bekenstein related the total entropy of a black hole directly to the area of event horizon and Boltzmann constant, and inversely to the square of Planck length. The proportionality constant was fixed using Hawking radiation.And thus was derived a beautiful relation, called the Bekenstein-Hawking formula:\\[S_{BH}= (\\frac{kA}{4l_{p}^{2}})\\]Consequently, four laws of black hole mechanics were also established, analogous to the four laws of thermodynamics. The zeroth law state that the event horizon of a stationary black hole has constant surface gravity which is analogous to temperature. The first law relates the change in energy to the change in area, angular momentum and electric charge. The second law states that the horizon area is a non-decreasing function of time. And the third law prohibits from forming black holes with zero surface gravity.Over the years, these laws have been somewhat modified as new data on observing black holes is analyzed. Hawking theorized that if a particle-antiparticle pair is created at the event horizon, one of them may be sucked in by the black hole before annihilation and the other emitted as so-called Hawking Radiation. After the hypothesis of Hawking radiation was proved, it was well understood that the horizon area and mass of a black hole decreases over time in open systems.In fact, black hole thermodynamics can be applied to more general systems as well. They have been used to show that cosmological event horizons/particle horizons (which essentially, is the boundary between observable and unobservable universe) also have an entropy and temperature. Recent studies have also shown that the proportionality between entropy and surface area can also be used to obtain new fluid models and derive surface tension in a novel way.A recent development of Holographic principle which states that the number of degrees of freedom of a system can be related to geometry of spacetime it is present in. This particular principle has huge implications on theories of quantum gravity. This principle makes use of Bekenstein-Hawking formula to a huge extent.Thus, further study of thermodynamics at such extreme conditions can really open new ways to observe and analyze the universe and can help in discovering unknown uses of heavily studied physics from new angles!Source: Scholarpedia; A liquid model analogue for Black hole thermodynamics by David Hochberg and Juan Perez-Mercader" } , { "title": "Stephen Hawking - The Man Who Pushed the Boundaries of Knowledge", "url": "http://blog.sedscelestia.org/Stephen-Hawking/", "date": "March 28, 2018", "category": "Uncategorized", "tags": ["Hawking"], "author": "Anonymous", "content": "“I’m not afraid of death, but I’m in no hurry to die. I have so much I want to do first.”– Stephen Hawking.Most of you are aware that our beloved theoretical physicist and cosmologist Stephen Hawking passed away on 14 March. His discoveries are his legacy and we present one of them to you. This one is about Hawking Radiation – Hawking’s most famous discovery.Now, our perception of a black hole was sort of straightforward before i.e. ‘a region in space from which nothing, not even light, can escape’. So a black hole is a literal hole in the universe, existing forever, only growing and never shrinking.Or we thought so, until Hawking came along and published a research paper in Journal ‘Nature’ titled ‘Black Hole Explosions’ suggesting that even black holes emit radiation. This radiation has been termed as ‘Hawking Radiation’. The question now arises that if Light cant escape the gravitational pull of a black hole and nothing travels faster than the speed of light, how is this ‘so called radiation’ escaping the clutches? The simplest explanation for the same is as followsQuantum field theory suggests that Space, as we see it, is filled with quantum fields. They oscillate with different frequencies much like the oscillations on a guitar string. A particle is like a node on the string. But there are underlying vibration modes present even without a particle. They fluctuate in energy due to quantum uncertainty and those fluctuations give us what we think of as ‘Virtual Particles’. In space random pairs of matter and antimatter spontaneously appear and then annihilate each other, briefly borrowing energy from the vacuum itself. But near a black hole, it just so might happen that one out that pair enters the event horizon leaving the other free to escape, taking a little energy with it. This particle is what makes up Hawking Radiation. That energy can’t come from nothing so that black hole pays the debt by losing that much energy and gradually losing all of it and eventually ‘dying’. We still haven’t physically encountered this radiation but the physics checks out so were almost sure that it exists. And if It does it might even get a posthumous Nobel Prize to Hawking.Stephen’s expectation from life when he was diagnosed with ALS dropped to zero. He said everything that had happened since is a Bonus. And what a bonus – for Physics, for the millions enlightened by his books and for the even larger number inspired by his achievements against all odds.And I’d like to end this blog with another one of his quotes, “My goal is simple. It is a complete understanding of the universe, why it is as it is and why it exists at all.”So here we bid adieu to the man who inspired us all as he leaves us for his infinite journey through the cosmos.Header Image Credits: BBC/RICHARD ANSETT" } , { "title": "Elon Musk pushes the boundries of humanity", "url": "http://blog.sedscelestia.org/Elon-Musk/", "date": "December 27, 2017", "category": "Uncategorized", "tags": ["Space_News"], "author": "Mudit Jain", "content": "A couple of months ago, our friend the Billionaire, philanthropist, entrepreneur and superhero (No, not Tony Stark) gave us a surprise as he declared SpaceX’s plans for Mars. Almost a year after he teased us with the same, he was back with a more detaileda version of how he plans to send people to Mars within the next 7 years.He started with introducing the BFR(Big Freaking rocket? Maybe.). A beast of a ship which can carry 150 tons of cargo and people into Space. This BFR can also launchsatellites into orbit, and ferry people from one part of Earth to another within 30 minutes. In addition to this, this ship is completely reusable (Awesome right!). All parts of the launch have the capability of landing back onto the launch pad. It can do manned missions to the moon to maybe create a moon base because Why not? SpaceX has also decided to stop the function of its more famous Falcon 9 and Falcon Heavy rockets and focus completely on this project.His plans include sending First missions to Mars by 2022followed by a manned mission as early as 2024. Spacex has never been less ambitious but this seems too far stretched even by their standards. As their so-called launch date comes near they are yet to develop the BFR and test it before trying for Mars. Added to that is the challenges of designing a habitat for Mars.So, do you think Elon Musk went a lot ahead of himself or will he be able to achieve his more than ambitious plan for a Mars Colony this soon enough? I would say that We are not far away from being a multiplanet species. Meanwhile, NASA and Boeing are also planning for manned missions to Mars and further. Lets just wait and see who is the first one to succeed and hope for the best. And while you’re at it, don’t forget to check out the rest of our blogs.Being the Musk fan that I am, how can I not ask you to follow their Twitter Handle? Go check it out!" } , { "title": "Lyman Alpha Blob", "url": "http://blog.sedscelestia.org/Lyman-Alpha-Blob/", "date": "November 25, 2017", "category": "Uncategorized", "tags": ["Observations"], "author": "Nikhil Bisht", "content": "Credit: NASAHave you ever looked up in the night sky and realized, there are so many celestial objects and phenomena we have discovered in the mere past four or five centuries? Well, the universe never ceases to baffle us, and it did so again in late 1990s, when some astronomers found ginormous gas clouds made almost entirely of hydrogen gas containing multiple galaxies. Yes, and by ginormous, I mean of sizes almost 4-5 times that of Milky Way! Even though being around 11.5 billion light years away, this “blob” in space glowed brightly, a phenomena that couldn’t be explained at that time. As they researched more, they found out that this particular specimen (named LAB-1, for obvious reasons) produced stars at the rate of almost 100 times than Milky Way! This is due to two very large galaxies residing at the center, being fueled with materials by smaller galaxies surrounding them. This mega-star production factory also emits light in the UV spectrum. Being so far away, the light gets red-shifted to the extent that it is seen as a Lyman Alpha line in the spectrum (hence the name). In the case of LAB1, the two central galaxies will eventually merge to form a massive elliptical galaxy.The fact that the light that reaches us from these blobs is mostly polarized, removes the possibility of the light being produced by the hydrogen gas, rather it assures us that in most of the cases, it is indeed the light from the galaxies inside, as that light would be polarized by scattering. The supermassive black holes in the center of older galaxies emit jets of radiation, further heating up the blob.The next question is, therefore, what is the nature of the environment around these central star-forming sources? I know, you’ll say, hydrogen gas. But that is the “observable” matter. What about dark matter? After intense measurements, it was found that the mass of the dark matter surrounding the LAB1 is of the order of 10 million trillion times the mass of sun! But, as of now, not much can be deduced from the data that we have, like how the gravitational field and other phenomena like radiation cooling in the blob affects the polarization of the emitted Lyman Alpha photons. What we do know is, that by understanding various phenomena related to them, we can have a better understanding of how primordial galaxies were formed. Being a relatively new observation, a lot is yet to be uncovered!Header Image Credits: Unknown" } , { "title": "Account Of A Fellow Wandering Star", "url": "http://blog.sedscelestia.org/Account-of-a-Fellow-Wandering-Star/", "date": "November 20, 2017", "category": "Uncategorized", "tags": ["Galaxy","Love","Personal","Science","Stars","Thought","Universe"], "author": "Gaurav Iyer", "content": "When I was a kid, I’d peer into the vast, black expanse called space through my television screen.It fascinated me to no extent.Space was like a canvas, upon which the most beautiful things in the universe (quite literally, the universe) were painted. I saw swirls of red, blue, green and yellow mixed together beautifully, and yet quite randomly to create a galaxy.That is my first memory of what space and the Universe might look like.And that is the time when I fell into the illusion that I was in love with what “space” and the Universe was. I think we all fell for that beautiful and deceptive illusion at first.I remember growing up and participating in an astronomy olympiad. It involved studying about all kinds of celestial bodies, like neutron stars, quasars, and pulsars. When I glanced through the book, I felt like, “Well, this is gonna be interesting.”And then, just like my other friends who were participating and who were as equally interested and in “love” with the Universe as I was, my interest wavered. I was required to learn various seemingly useless facts, like the mass of a specific celestial body, or the colour of stars depending on their coolness or hotness.Until that time, all that I thought was the study of the Universe would involve looking at colourful and pretty things in the sky.Man, was I wrong. The illusion had shattered.The beauty and colours in space isn’t all that’s there to it. There’s a lot more going on, other than what the television shows us.There’s a lot more patience, calculations, observations and diligence that goes into the construction of a science as beautiful as that of the Universe. And most of these will be seemingly boring things.But when the pieces all come together, and show what happens and why it happens, it fills you with a sense of happiness that doesn’t seem to fade, and a burning desire to know and learn more. That “Eureka!” moment, when you finally figure it out.It’s all completely worth it.And that is what a love for the Universe truly feels like. You don’t just love it for it’s outward appearances, you also love all it’s details, mechanisms and flaws (lots of these in this field as of now :P).I might not have won the Olympiad, but it gave me the opportunity to dig deeper into this field. I did some of my own research on the side, saw how it all comes together, and realised that the Universe is so much more beautiful than what it just looks like, if you try to understand what actually goes on out there.That’s saying a lot in itself, because it’s beautiful as it is.To love it for all that it actually is, and not just what it looks like is a difficult feat, and to show dedication towards it is harder. And that is what makes the disciples of this science so much more awesome." } , { "title": "Boyajian’s Star: The star which is slowly losing its soul", "url": "http://blog.sedscelestia.org/Boyajian's-Star/", "date": "September 23, 2017", "category": "Science Space_News", "tags": ["Alien","Astronomy","Boyajian","Cosmology","Kepler","KIC_8462852","Star","Taby"], "author": "Anonymous", "content": "In science, we do not simply accept theories. Every new discovery goes through a series of steps to establish itself. If we see a streak of light in the sky, we cannot jump to the conclusion that it’s a UFO landing on earth. Most probably it is a meteor. But to establish that, we have to think in a logical manner to reach the right conclusion. But what if all the evidence point towards the most unlikely occurrence? Once you eliminate the impossible, whatever remains, no matter how improbable, must be the truth. This is what happened when the world of astronomy shifted its gaze toward the star KIC 8462852 better known as Boyajian’s star during the Kepler’s mission.Kepler space program was launched by NASA to find Earth like planets in other solar systems. It does so by measuring the dip in the brightness of star when the planet of its system pass in front of it. Depending upon how large is the dip in the intensity of light measured, the size of the planet is calculated. The passing is known a transit: When a planet whose orbit is aligned to our line of sight passes in front of a star blocking a part of it’s light.When the Boyajian’s Star was first observed, the data of the transit suggested that whatever passed from in front of the star had the size of Jupiter. Now, normally a transit lasts for a few hours, but this transit lasted for weeks and it was asymmetric.Figure 1: Jupiter’s TransitHot Jupiter light curves from Kepler (red, bottom) and K2 (blue, top). K2 data is dominated by jagged noise that was not present during the original Kepler mission.Src: K2 dataIn the transit, the dip observed is rarely more than 1 percent of the intensity of star light. On March 2011, a 15 percent dip was observed from the transit of Boyajian’s star. Then in February 2013, a series of dips were observed. Some lasted 1-2 days, some for weeks, for a period of 100 days, at last when, the Kepler mission ended. This time, the dips were almost 20 percent i.e. the object had an area of one thousand times that of Earth.Figure 2: The transit of object orbiting the Boyajian’s starCredit: T. Boyajian & team/MNRASVarious hypotheses were proposed to explain the data collected by Kepler. The first suggested the presence of Protoplanetary debris disk. This only happens when a star is young, which this star was not. The second was Catastrophic collision, very similar to Earth-Moon formation. If it was indeed the case, then a glow must have been observed due to the heating of the debris from the heat of the sun in the form of infrared rays, which was not observed. As both the hypothesis failed to explain the data, they were rejected.The other explanation was that a huge swarm of comets orbits the star in a very elliptical orbit. It would take hundreds of comets to match the collected data, and those comets will be the ones between our line of sight and the star, suggesting that the total number may be in thousands. Also, this many comets means the presence of lots of dust which was already proven to be absent.Due to the 20% dip, the object must be as large as the star itself, so that rules out planets, which can have a maximum radius of 50,000km. Stars can also be excluded and Boyajian’s Star has no nearby companion. So what is the possible explanation of these observations?This is the part where it gets interesting. Let’s first see a picture, a representation of what is proposed as a possible explanation.Figure 3: Alien Mega structureCredit: Danielle Futselaar/SETI InternationalWhat we see here is a giant mega structure around the star. The explanation that was proposed says that it is possible that an advanced alien civilization, which has already exhausted its planet’s resources, is using the star as its energy source and has built giants solar panels around the star. The size of a single component of this structure is around 25 million miles. This will explain the deep dips and the asymmetry of the transit. But this is still only a hypothesis and a very unlikely one at that. But who knows, this maybe the first sign of an intelligent species outside our planet. We will let the future decide that.Header Image Credits: NASA/JPL-Caltech" } , { "title": "For the First Time, Orbiting Supermassive Black Holes Have Been Observed", "url": "http://blog.sedscelestia.org/For-The-First-Time,-Orbiting-Supermassive-Black-Holes-Have-Been-Observed/", "date": "June 29, 2017", "category": "Space_News", "tags": ["Black_Holes"], "author": "Anonymous", "content": "In a major discovery, astronomers have observed a pair of supermassive black holes orbiting each other, hundreds of millions of light years away.The discovery is the result of more than two decades of work, and an incredible feat considering the precise measurements required. Understanding the nature of such interactions will give us a greater understanding of how galaxies, and the universe, have evolved.“For a long time, we’ve been looking into space to try and find a pair of these supermassive black holes orbiting as a result of two galaxies merging,” says Greg Taylor,one of the researchers, from The University of New Mexico (UNM).“Even though we’ve theorised that this should be happening, nobody had ever seen it until now.”The team observed the pair of black holes in a galaxy, named 0402+379, roughly 750 million light years from Earth.VLBA map of radio galaxy 0402+379 at 15 GHz.Credit: UNMAccording to Karishma Bansal, the first author on the paper, also from UNM, the combined mass of these supermassive black holes is about 15 billion times that of our sun, and their orbital period is around 24,000 years.This means that even though the team has been observing these black holes for over a decade, they haven’t been able to detect even the slightest curvature in their orbit.“If you imagine a snail on the recently-discovered Earth-like planet orbiting Proxima Centauri – 4.243 light years away – moving at 1cm [0.4 inches] a second, that’s the angular motion we’re resolving here,” explains Roger W. Romani, one of the researchers from Stanford University.Black holes are notoriously difficult to study because they cannot be directly observed, but can only be detected from their effect on nearby matter.So, to find the orbit of these black holes, the UNM team used the Very Long Baseline Array (VLBA), which is composed of 10 radio telescopes. By measuring the various frequencies of radio signals emitted by the black holes, the team was then able to plot their trajectory.“When Dr. Taylor gave me this data I was at the very beginning of learning how to image and understand it,” says Bansal.“And, as I learned there was data going back to 2003, we plotted it and determined they are orbiting one another. It’s very exciting.” The technical achievement of this discovery is a triumph and will vastly improve our understanding of these enigmatic objects.Ever since Einstein’s theory of general relativity, astronomers have been fascinated by supermassive black holes. Recently, there have been several new discoveries about black holes, but there’s still a lot about them that we don’t know.Continuing to observe the orbit and interaction of these black holes will reveal a lot about where our galaxy came from, where it might be heading in the future and the role that black holes play in this process.Currently, the Andromeda galaxy, which also contains a supermassive black hole, is projected to collide with our Milky Way – making the event that the UNM team is observing our galaxy’s potential future in a few billion years.“Supermassive black holes have a lot of influence on the stars around them and the growth and evolution of the galaxy,” says Taylor.“So, understanding more about them and what happens when they merge with one another could be important for our understanding for the universe.”The UNM team will come back to these black holes in a few years time to confirm observations and improve their projections around orbits and trajectories.For now, we can enjoy the fact they’ve finally delivered a direct observation for the first time and no doubt will inspire other work to push forward amongst the wider scientific world.The paper was published in The Astrophysical Journal with a pre-print version available on arXiv." } , { "title": "Physicists Have Figured Out Where The Sun’s Plasma Jets Come From", "url": "http://blog.sedscelestia.org/Physicists-Have-Figured-Out-Where-The-Sun-s-Plasma-Jets-Come-From/", "date": "June 25, 2017", "category": "Uncategorized", "tags": ["Plasma_Jets"], "author": "Anonymous", "content": "After over a century of observations and several theories, scientists may have finally nailed the origin of the high-speed plasma blasting through the Sun’s atmosphere several times a day. Using a state-of-the-art computer simulation, researchers have developed a detailed model of these plasma jets, called spicules.The new findings answer some of the bigger questions in solar physics, including how these plasma jets form and why the Sun’s outer atmosphere is far hotter than the surface.“This is the first model that has been able to reproduce all the features observed in spicules,” Juan Martinez-Sykora, lead author and astrophysicist at the Bay Area Environmental Research Institute in California, told ScienceAlert.Every five minutes, spicules shoot red hot streams of charged particles into the corona, the outer layer of the solar atmosphere, at around 150 kilometres (93 miles) per second (paper). Lasting up to 15 minutes it is estimated that up to 300,000 spicules are active at any one time.The bizarre thing about the corona is that it’s totally counterintuitive when it comes to temperature.Even though it’s further away, it’s millions of degrees hotter than the Sun’s surface, thanks to the constant supply of hot plasma delivered by the spicules. This jump in temperature is kind of like standing some distance away from a bonfire and feeling hotter than the fire itself.While scientists have been aware of spicules for over a century, their origin has remained a puzzle. Over the years, there have been several theories that have attempted to crack the mystery.One study suggested that spicules are generated by massive sound waves, while a more recent study proposed that their formation is due to the magnetic field forming loops out of the atmosphere.But these theories only provided fragments of the story which failed to explain the origin of spicules and why they are found all over the sun.Speaking with ScienceAlert, Lockheed and Martin Solar and Astrophysics Laboratory principal physicist Bart de Pontieu said observing the spicules from the ground has its limitations.“It’s been very hard to get a clear view of what these spicules do, as Earth’s atmosphere creates a murky picture,” said de Pontieu, who was also a co-author on the paper. “But thanks to space telescopes, we can now see what they really look like in greater detail.”And now, Martinez-Sykoro and his team have developed a computer model that can generate simulations of these powerful plasma jets in action, allowing the researchers to track different temperatures and physical features.The numerical model revealed that the formation of spicules happens in three distinct stages.The process begins on the surface of the Sun where churning plasma interacts with the magnetic fields, which get twisted up and knotted in the process. This distortion creates strong magnetic tension trapped close to the surface.Next, neutral and charged particles mix above the surface in a process called ambipolar diffusion, which creates an escape route for the building magnetic tension. Then, like a slingshot, the magnetic tension is violently released into the atmosphere and out into space at staggering speed.“These jets of plasma are ejected so fast that they could traverse the length of California in just a couple of minutes,” De Pontieu told ScienceAlert. “They can reach heights of 10,000 kilometres, roughly the diameter of Earth, in just five to ten minutes.”To see how the simulations stacked up against the real thing, the team analysed data from NASA’s Interface Region Imaging Spectrograph and the Swedish Solar Telescope. They found that the simulations recreated the properties of actual spicules, including the size, speed and shape.In addition to solving the long-held mystery of how spicules form, the new findings demonstrate how the plasma jets blast millions of degrees of heat into the scorching corona.“It’s exciting because it explains why the solar atmosphere is millions of degrees hotter than the surface,” De Pontieu told ScienceAlert.Now that scientists know how spicules form, they can take a closer look at how they interact with the outer reaches of the solar atmosphere.The study has been published in Science." } , { "title": "NASA Has Discovered Hundreds of Potential New Planets – 10 of them are potential Second-Earth candidates", "url": "http://blog.sedscelestia.org/Potential-New-Planets/", "date": "June 21, 2017", "category": "Uncategorized", "tags": ["Science"], "author": "Anonymous", "content": "NASA scientists on Monday announced the discovery of 219 new objects beyond our solar system that are almost certainly planets.What’s more, 10 of these worlds may be rocky, about the size of Earth, and habitable.The data comes from the space agency’s long-running Kepler exoplanet-hunting mission. From March 2009 through May 2013, Kepler stared down about 145,000 sun-like stars in a tiny section of the night sky near the constellation Cygnus.Most of the stars in Kepler’s view were hundreds or thousands of light-years away, so there’s little chance humans will ever visit them — or at least any time soon. However, the data could tell astronomers how common Earth-like planets are, and what the chances of finding intelligent extraterrestrial life might be.“We have taken our telescope and we have counted up how many planets are similar to the Earth in this part of the sky,” Susan Thompson, a Kepler research scientist at the SETI Institute, said during a press conference at NASA Ames Research Center on Monday.“We said, ‘how many planets there are similar to Earth?’ With the data I have, I can now make that count,” she said. “We’re going to determine how common other planets are. Are there other places we could live in the galaxy that we don’t yet call home?”Added to Kepler’s previous discoveries, the 10 new Earth-like planet candidates make 49 total, Thompson said. If any of them have stable atmospheres, there’s even a chance they could harbour alien life.THE NEW EARTHS NEXT DOOR?NASA/JPL-CaltechScientists wouldn’t say too much about the 10 new planets, only that they appear to be roughly Earth-sized and orbit in their stars’ “habitable zone” — where water is likely to be stable and liquid, not frozen or boiled away. That doesn’t guarantee these planets are actually habitable, though. Beyond harboring a stable atmosphere, things like plate tectonics and not being tidally locked may also be essential.However, Kepler researchers suspect that almost countless Earth-like planets are waiting to be found. This is because the telescope can only “see” exoplanets that transit, or pass, in front of their stars.The transit method of detecting planets that Kepler scientists use involves looking for dips in a star’s brightness, which are caused by a planet blocking out a fraction of the starlight (similar to how the moon eclipses the sun).https://gfycat.com/ifr/UnhappyTastyGermanspanielBecause most planets orbit in the same disk or plane, and that plane is rarely aligned with Earth, that means Kepler can only see a fraction of distant solar systems. (Exoplanets that are angled slightly up or down are invisible to the transit method.)Despite those challenges, Kepler has revealed the existence of 4,034 planet candidates, with 2,335 of those confirmed as exoplanets. And these are just the worlds in 0.25% of the night sky.“In fact, you’d need 400 Keplers to cover the whole sky,” Mario Perez, a Kepler program scientist at NASA, said during the briefing.The biggest number of planets appear to be a completely new class of planets, called “mini-Neptunes,” Benjamin Fulton, an astronomer at the University of Hawaii at Manoa and California Institute of Technology, said during the briefing.Such worlds are between the size of Earth and the gas giants of our solar system, and are likely the most numerous kind in the universe. “Super-Earths,” which are rocky planets that can be up to 10 times more massive than our own, are also very common.NASA/Kepler/Caltech (T.Pyle)While just 49 of Kepler’s thousands of planet candidates are Earth-sized and in a habitable zone, the discovery has rocked the scientific world: This could mean that billions of such worlds exist in the Milky Way galaxy alone.“This number could have been very, very small,” Courtney Dressing, an astronomer at Caltech, said during the briefing. “I, for one, am ecstatic.”KEPLER’S BIG BACK-UP PLANNASA Ames/W. Stenzel and JPL-Caltech/R. HurtKepler finished collecting its first mission’s data in May 2013. It has taken scientists years to analyse that information because it’s often difficult parse, interpret, and verify.Thompson said this new Kepler data analysis will be the last for this leg of the telescope’s first observations. Kepler suffered two hardware failures (and then some) that limited its ability to aim at one area of the night sky, ending its mission to look at stars that are similar to the sun.But scientists’ back-up plan, called the K2 mission, kicked off in May 2014. It takes advantage of Kepler’s restricted aim and uses it to study a variety of objects in space, including supernovas, baby stars, comets, and even asteroids.Although K2 is just getting off the ground, other telescopes have had success in these types of endeavours. In February, for example, a different one revealed the existence of seven rocky, Earth-size planets circling a red dwarf star.NASA/JPL-CaltechAn illustration of what it might look like on the surface of TRAPPIST-1f, a rocky planet 39 light-years away from Earth.Such dwarf stars are the most common in the universe and can have more angry outbursts of solar flares and coronal mass ejections than sun-like stars.But paradoxically, they seem to harbor the most small, rocky planets in a habitable zone in the universe — and thus may be excellent places to look for signs of alien life.This article was originally published by Business Insider." } , { "title": "In a World-First, Scientists Have Achieved ‘Liquid Light’ at Room Temperature", "url": "http://blog.sedscelestia.org/Liquid-Light/", "date": "June 21, 2017", "category": "Uncategorized", "tags": ["Science"], "author": "Anonymous", "content": "For the first time, physicists have achieved ‘liquid light’ at room temperature, making this strange form of matter more accessible than ever.This matter is both a superfluid, which has zero friction and viscosity, and a kind of Bose-Einstein condensate – sometimes described as the fifth state of matter – and it allows light to actually flow around objects and corners.Regular light behaves like a wave, and sometimes like a particle, always travelling in a straight line. That’s why your eyes can’t see around corners or objects. But under extreme conditions, light can also act like a liquid, and actually flow around objects.Bose-Einstein condensates are interesting to physicists because in this state, the rules switch from classical to quantum physics, and matter starts to take on more wave-like properties.They are formed at temperatures close to absolute zero and exist for only fractions of a second.But in this study, researchers report making a Bose-Einstein condensate at room temperature by using a Frankenstein mash-up of light and matter.“The extraordinary observation in our work is that we have demonstrated that superfluidity can also occur at room-temperature, under ambient conditions, using light-matter particles called polaritons,” says lead researcher Daniele Sanvitto, from the CNR NANOTEC Institute of Nanotechnology in Italy.Creating polaritons involved some serious equipment and nanoscale engineering.The scientists sandwiched a 130-nanometre-thick layer of organic molecules between two ultra-reflective mirrors, and blasted it with a 35 femtosecond laser pulse (1 femtosecond is a quadrillionth of a second).“In this way, we can combine the properties of photons – such as their light effective mass and fast velocity – with strong interactions due to the electrons within the molecules,” says one of the team, Stéphane Kéna-Cohen from École Polytechnique de Montreal in Canada.The resulting ‘super liquid’ had some strange properties.Under normal conditions, when liquid flows, it creates ripples and swirls – but that’s not the case for a superfluid.As you can see below, the flow of polaritons is disturbed like waves under regular circumstances, but not in the superfluid:The flow of polaritons encounters an obstacle in non-superfluid (top) and superfluid (bottom).Credit: Polytechnique Montreal“In a superfluid, this turbulence is suppressed around obstacles, causing the flow to continue on its way unaltered,” says Kéna-Cohen.The researchers say the results pave the way not only to new studies of quantum hydrodynamics, but also to room-temperature polariton devices for advanced futuretechnology, such as the production of super-conductive materials for devices such as LEDs, solar panels, and lasers.“The fact that such an effect is observed under ambient conditions can spark an enormous amount of future work,” says the team.“Not only to study fundamental phenomena related to Bose-Einstein condensates, but also to conceive and design future photonic superfluid-based devices where losses are completely suppressed and new unexpected phenomena can be exploited.”The findings were reported in Nature Physics.Article originally published on Science Alert." } , { "title": "This New Explanation For Dark Matter Could Be The Best One Yet", "url": "http://blog.sedscelestia.org/Dark-Matter-New-Explanation/", "date": "June 21, 2017", "category": "Uncategorized", "tags": ["Science"], "author": "Anonymous", "content": "It makes up about 85 percent of the total mass of the Universe, and yet, physicists still have no idea what dark matter actually is.But a new hypothesis might have gotten us closer to figuring out its identity, because physicists now suspect that dark matter has been changing forms this whole time – from ghostly particles in the Universe’s biggest structures, to a strange, superfluid state at smaller scales. And we might soon have the tools to confirm it.Dark matter is a hypothetical substance that was proposed almost a century ago to account for the clear imbalance between the amount of matter in the Universe, and the amount of gravity that holds our galaxies together.We can’t directly detect dark matter, but we can see its effects on everything around us – the way galaxies rotate and the way light bends as it travels through the Universe suggests there’s far more at play than we’re able to pick up.And now two physicists propose that dark matter has been changing the rules this whole time, and that could explain why it’s been so elusive.“It’s a neat idea,” particle physicist Tim Tait from the University of California, Irvine, who wasn’t involved in the study, told Quanta Magazine.“You get to have two different kinds of dark matter described by one thing.”The traditional view of dark matter is that it’s made up of weakly interacting particles such as axions, which are influenced by the force of gravity in ways that we can observe at large scales.This ‘cold’ form of dark matter can be used to predict how massive clusters of galaxies will behave, and fits into what we know about the ‘cosmic web’ of the Universe – scientists suggest that all galaxies are connected within a vast intergalactic web made up of invisible filaments of dark matter.But when we scale down to individual galaxies and the way their stars rotate in relation to the galactic center, something just doesn’t add up.“Most of the mass [in the Universe], which is dark matter, is segregated from where most of the ordinary matter lies,” University of Pennsylvania physicist Justin Khoury explains in a press statement.“On a cosmic web scale, this does well in fitting with the observations. On a galaxy cluster scale, it also does pretty well. However, when on the scale of galaxies, it does not fit.”Khoury and his colleague Lasha Berezhiani, now at Princeton University, suggest that the reason we can’t reconcile dark matter’s behaviour on both large and small scales in the Universe is because it can shift forms.We’ve got the ‘cold’ dark matter particles for the massive galaxy clusters, but on a singular galactic scale, they suggest that dark matter takes on a superfluid state.Superfluids are a form of cold, densely packed matter that has zero friction and viscosity, and can sometimes become a Bose-Einstein condensate, referred to as the ‘fifth state of matter’.And as strange as they sound, superfluids are starting to appear more accessible than ever before, with researchers announcing just last week that they were able to create light that acts like a liquid – a form of superfluid – at room temperature for the first time.The more we come to understand superfluids, the more physicists are willing to entertain the idea that they could be far more common in the Universe than we thought.“Recently, more physicists have warmed to the possibility of superfluid phases forming naturally in the extreme conditions of space,” Jennifer Ouellette explains for Quanta Magazine.“Superfluids may exist inside neutron stars, and some researchers have speculated that space-time itself may be a superfluid. So why shouldn’t dark matter have a superfluid phase, too?”The idea is that the ‘halos’ of dark matter that exist around individual galaxies create the conditions necessary to form a superfluid – the gravitational pull of the galaxy ensures that it’s densely packed, and the coldness of space keeps the temperature suitably low.Zoom out to a larger scale, and this gravitational pull becomes too weak to form a superfluid.The key here is that the existence of superfluid dark matter could explain the strange behaviours of individual galaxies that gravity alone can’t explain – it could be creating a second, as-yet-undefined force that acts just like gravity within the dark matter halos surrounding them.As Ouellette explains, when you disturb an electric field, you get radio waves, and when you disturb a gravitational field, you get gravitational waves. When you disturb a superfluid? You get phonons (sound waves), and this extra force could work in addition to gravity.“It’s nice because you have an additional force on top of gravity, but it really is intrinsically linked to dark matter,” Khoury told her. “It’s a property of the dark mattermedium that gives rise to this force.”We should be clear that this hypothesis is yet to be peer-reviewed, so this is all squarely in the realm of the hypothetical for now. But it’s been published on the pre-print website arXiv.org for researchers in the field to pick over.A big thing it has going for it is the fact that it could also explain ‘modified Newtonian dynamics’ (MOND) – a theory that says a modification of Newton’s laws is needed to account for specific properties that have been observed within galaxies.“In galaxies, there is superfluid movement of dark matter and MOND applies. However, in galaxy clusters, there is no superfluid movement of dark matter and MOND does not apply,” the team suggests in a press statement.We’ll have to wait and see where this hypothesis goes, but the Khoury and Berezhiani say they’re close to coming up with actual, testable ways that we can confirm their predictions based on superfluid dark matter.And if their predictions bear out – we might finally be onto something when it comes to this massive cosmic mystery.The research is available online: Theory of Dark Matter SuperfluidityThis article was originally published by Science Alert." } , { "title": "Why Science?", "url": "http://blog.sedscelestia.org/Why-Science/", "date": "June 3, 2017", "category": "Uncategorized", "tags": ["Observations"], "author": "Hareesh Nair", "content": "Humans are a tiny speck in this vast universe. We have always been curious and we have this intuitive evolutionary thirst to answer every question. This species having a more developed brain began to consider questioning what we see and feel as an important component to progress apart from food and mating.HypothesisOne approach is to observe and make a hypothesis based on the boundations of known math and imagination. A person in the metal age observing sparks coming from a hammer striking on a metal piece could immediately draw an analogy to the lightning strikes lighting up the sky. The hypothesis was simple and straight forward. There is a large hammer up there creating these sparks. That should be so logical. Now, let’s draw some conclusion from this hypothesis which is very likely correct. There must be some superhuman being who can handle such a big hammer. A super powered god who can create lightning upon his will with his super powered hammer. We don’t know his name but let’s call him Thor.Option ALet’s say people like this theory and they accept it because it is supposedly relatable, logical and satisfies the hunger for curiosity. It is clear and convenient idea. Now, for science to progress (yes, it was science back then), let’s not have people who would interfere and try to manipulate or disorder the axioms and hypothesis our understanding of world is built on. Let’s burn the people who question our axioms or try to prove us wrong. People who claim it to be electrical discharge between two clouds or people who claim it’s a giant cat’s hair rubbing against the earth. We don’t need negativity and suppression on the path to understanding the universe. Let’s call it option A.Option BPeople like this theory and they accept it. However, they are open to questioning and challenging their own model to test its credibility and reliability because questioning is what led them to establish their set of axioms. The process of questioning which always lets open a door to truth, which would make them realize their mistakes is what will take them ahead and is ultimately what will help them progress. It may slow down the progress of an existing set of ideas but it will never, on a large scale of time, be something which slowed them down. It is more like increasing the clarity and moving on a better direction at a slower pace than just going ahead without a realization of what you are and how terribly wrong your approach regarding understanding the universe could be. So, we stop and acknowledge both individuals who claim that lightning is because of clouds or cats and we go with the more logical option. The option which answers further questions efficiently. Let’s call this option B.Now why science? Because science is option B. The process that we follow to establish the foundation of science, we are ready to question it as well. Just the fact that you can question science and there will be an answer makes science credible. And if there is not an answer to the question, it’s even better, that’s when you change those pillars. That’s when you redefine science. That’s when you discover something new. A hidden face of this universe unveiling in front of you. Now, if someone says that times slows down in a moving frame, you cannot choose to refuse it. It’s not an opinion. It’s just how the world works. Doesn’t mean that you cannot question it. You can always question the reliability of the conclusions drawn from an experiment or how a hypothesis is unstable or stable. You always have the liberty to choose, to do, to manipulate, to find a better solution and whatever logically is right will be accepted.Towards a more philosophical aspect. If someone says the Earth is flat or vaccines are not good or cancer is a propaganda, we have two options. A or B? We can refuse them, refuse to acknowledge and ignore them. We can progress with what we believe is right. Follow the methodical system we follow to establish science which we personally chose as a right option. Or we can wait and consider conflicting contradicting opinions. Slow down science for a second and ensure are we on the right track? If no, go back and fix where we went wrong. If yes, provide a reasoning to why the system is still consistent and go ahead at the original pace we are meant to go.If we believe in science, it would be self-contradictory to not acknowledge the fact that science has to progress such that we prioritize clarity over speed." } ]}