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DEFINITION,UNIVERSE, CONSTELLATIONS, GALAXY, SOLAR SYSTEM, ROCKET, SATELLITES, CHANDRAYAN MISSION , INDIA'S MISSION MARS.

DEFINITION,UNIVERSE, CONSTELLATIONS, GALAXY, SOLAR SYSTEM, ROCKET, SATELLITES, CHANDRAYAN MISSION , INDIA'S MISSION MARS.

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    Astronomy Astronomy Presentation Transcript

    • d.b.gaekwad TGT/S.SC. , JNV PARBHANI
    • aSTRONOMY- MYSTRY ReVeaLed
    • aSTRONOMY - MeaNINg The word Astronomy is derived from the greek word , “Astron” meaning , “ Star” and “Nomy”, is derived from the word , “ Nomos” means , “ Law or Culture” . Astronomy is a , “Law or Culture of Stars”. Astronomy is a natural science , that is the study of Celestial objects- planets, stars, moons , nabulae and galaxies. The physics, chemistry, mathematics of evolutions of such objects out side the earth’s atmoshphere
    • eaRLY aSTRONOMeRS  Astronomer - Astronomers use the principles of physics and mathematics to learn about the fundamental nature of the universe, including the sun, moon, planets, stars, ...  Nicholas Copernicus – (1473 – 1543) the first astronomer to teach that the sun (not the Earth) was the center of the solar system.  Galileo Galilei – built the first telescope in 1609 and proved Copernicus correct.
    • whaT IS OuT TheRe? • Ever since mankind has looked up at the moon and stars, we have wandered about life in the universe.
    • whaT IS a uNIVeRSe ? • The Universe is commonly defined as the totality of existence, including planets, stars, galaxies, the contents of intergalactic space, and all matter and energy. • The universe was born with the Big Bang as an unimaginably hot, dense point. When the universe was just 10-34 of a second or so old
    • CONSTeLLaTION
    • hOw bIg IS The uNIVeRSe? • Billions of stars – planets – galaxies
    • The uNIVeRSe • A small portion can be observed only of the entire universe. • Because the universe is only about 14 billion years old, light has only had about 14 billion years to travel through it. Therefore, the most distant regions of the universe we can see are about 14 billion light-years away. • This is the extent of the "observable universe," but the entire universe is probably much larger. It could even extend infinitely in all directions.
    • LIghT YeaR A light year is a unit of distance It is the distance that light can travel in one sidereal year Light moves at a velocity of about 300,000 kilometers each second So 300,000 km/sec x 60 sec/min x 60 min/hr x 24 hr/day x 365 days/year or: In one year light can travel about 9.46 trillion kilometers
    • LIghT YeaR • More specifically, a light year is defined as the distance a photon would travel, in free space and infinitely far from any gravitational or magnetic field in one Julian year (365.25 days of 86400 seconds each) • Light is used to measure distance since it is the fastest thing in the Universe
    • LIGHT YEAR
    • whaT IS a LIghT YeaR • A light year is a unit of distance, NOT a unit of time • A light minute and a light second are units related to the light year • A light minute is equal to 17,987,547 kilometers • A light second is equal to 299,793 kilometers • The Moon is 1.2 light seconds away from Earth
    • whaT IS LIghT YeaR The Solar System Our entire Solar System out to Pluto is only one eight-hundredth of a light year across The distance to our nearest neighbors, Alpha Centauri and Proxima Centauri, is 4.3 light years
    • whaT IS a LIghT YeaR • Our Milky Way Galaxy is 100,000 light years across Milky Way Galaxy • The distance to our nearest galaxy, the Andromeda Galaxy, is 2,300,000 light years • Recently the Universe has been calculated to be at least 156 billion light years across
    • LIghT YeaR: gOINg baCk IN TIMe Because a light year is directly related to the time light takes to travel through space, it follows that as we look out into the universe we also look back in time If a star is 1 million light years away, it has taken 1 million years for the light to reach us, and the light we are seeing was created 1 million years ago So we are seeing the star as it looked 1 million years ago, not how it looks today
    • whaT IS LIghT YeaR The Crab Nebula In about 5,350 BC a star in the constellation Taurus exploded That star was about 6,300 light years away from Earth meaning that the light from the explosion took 6,300 years to cross the intervening space That light finally reached Earth in 1054 AD —that was the date Earthbound observers saw the explosion that created the Crab Nebula Therefore when we look at the Crab Nebula today we see it as it as it was in about 4,300 BC
    • aSTRONOMICaL uNIT  The distance from Earth to the Sun is one Astronomical Unit.  The A.U. helps make the vast distances in our Solar System more manageable  Anything closer than Earth is a fraction of an A.U.  Anything further away is a multiple of an A.U.
    • TheORIeS ON ORIgIN OF OuR eaRTh  GEORGES DE BUFFON’S THEORY OF COMET’S COLLISION.  EMANUEL KANT’S THEORY OF GASEOUS MATTER.  INTER STELLER DUST HYPOTHESIS OF OTTO SCHMIDST.  BINARY STAR HYPOTHESIS OF RUSSEL & LITTLETON
    • geORgeS de buFFON’S TheORY  A Comet about to collide with the Sun.  The Collision results in release of material from the Sun.  Released material condenses and acquires the shape of planets which starts revolving around the Sun.
    • LIMITaTIONS TO The TheORY  Buffon’s theory fails to explain the peculiar position of planets around the sun which are arranged in such a manner that the largest ones occupy the middle orbits while the smaller ones occupy the marginal orbits.
    • eMaNueL kaNT’S TheORY OF gaSeOuS MaTTeR  Cold fragments of the primordial matter attracted towards each other by gravitational pull.  High temperature and angular velocity transform the matter into a gaseous state.  Centrifugal force throws out concentric rings of the gaseous matter.  Concentric rings condense and acquire the shape of Planets and Sub Planets.
    • LIMITaTIONS TO The TheORY  Failed to explain the sudden coming into play of the gravitational pull and the source of angular motion for the particles.
    • INTeR STeLLeR duST hYPOTheSIS OF OTTO SChMIdST  Dust particles revolving around the Sun under the influence of the gravitational pull.  The dust particles starts consolidating by colliding with one another.  Eventually nine planets and their sub planets emerge.
    • LIMITATIONS TO THE THEORY  Schmidst failed to explain the primordial existence of dust, clouds and their attraction towards the Sun considering the great distances between Stars in the Universe
    • BINARY STAR HYPOTHESIS OF RUSSEL & LITTLETON  The Sun existed in “Binary Companionship” with a “Companion Star”.  A third star happened to pass by this Binary arrangement.  Pull being exerted upon the companions star by the sun and the third star resulting in separation of materials from the companion star.  Fragments of the companion star getting transformed into planets which revolves around the Sun.
    • LIMITATIONS TO THE THEORY  This hypothesis does not explain the placement of the Planets in different orbits at varying distances from the Sun.
    • GALAXY  The word galaxy is derived from the Greek word “ Galaxias”  literally “Milky",   Galaxies range from dwarfs with as few as ten million (107) stars to giants with one hundred trillion (1014) stars,each orbiting their galaxy's own center of mass.  Galaxies contain varying numbers of star systems, star clusters and types of interstellar clouds. In between these objects is a sparse interstellar medium of gas, dust, and cosmic rays. Super massive black holes reside at the center of most galaxies. They are thought to be the primary driver of active galactic nuclei found at the core of some galaxies. The Milky Way galaxy is known to harbor at least one such object.
    • GALAXY
    • THE NAME OF OUR GALAXYAAKASH GANGA MILKY WAY • The name of our galaxy is the Milky Way. Our Sun and all of the stars that you see at night belong to the Milky Way. When you go outside on a dark night and look up, you will see a milky, misty-looking band stretching across the sky. When you look at this band, you are looking into the densest parts of the Milky Way, the "disk" and the "bulge."
    • WHERE IS THE SUN LOCATED  The Sun is near the inner rim of The Sun's location in  the Milky Way Galaxy.  The angles represent  longitudes in  the galactic coordinate  system. the Galaxy's Orion Arm.  The Sun is currently 16–98 Light year from the central plane of the Galactic disk.  It takes the Solar System about 240 million years to complete one orbit of the Galaxy (a Galactic year),so the Sun is thought to have completed 18–20 orbits during its lifetime and 1/1250 of a revolution since the origin of humans.
    • WHAT IS A GALACTIC YEAR  The galactic year, also known as a cosmic year, is the  duration of time required for the Solar  System to orbit once around the center of the Milky  Way Galaxy.  Estimates of the length of one orbit range from 225 to  250 million "terrestrial" years.  According to NASA, the Solar System is traveling at  an average speed of 828,000 km/h (230 km/s) or  514,000 mph (143 mi/s) relative to the galactic  center,which is about one 1300th of the speed of light.  If you could travel at that speed in a jet aircraft along  the equator, you would go all the way around the world  in approximately 2 minutes and 54 seconds.
    • WHERE ARE YOU IN THE UNIVERSE • 25,000 light years from the galaxy center, in the Orion Arm, which is roughly halfway between the center and the edge. • its at the edge near one of the spiral ends...... • we’re located in a minor arm of the galaxy. Our local spiral arm is sometimes Orion Arm, or sometimes the Orion Spur. It’s between the Sagittarius and Perseus Arms of the Milky Way.
    • SOLAR SYSTEM
    • SOLAR SYSTEM
    • SOLAR SYSTEM • A solar system is the collection of planets, asteroids, and moons (moons orbit the planets) that occupy a space around a sun and are held within the gravitational pull of the Sun. Our solar system consists of eight planets (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune) and a planetoid, Pluto.
    • PLANETS- DEFINITIONS  The word planet is derived from the Greek word, “Planetai” which means a “Wandering Star”.  On september 13,2006 International Astronomical Union  adopted the following definition of a Planet:A. A "planet“ is a celestial body that is in orbit around the Sun . B. Has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape. C.Has cleared the neighborhood around its orbit. i.e. doesn’t allow any other celestial object to intersect its orbit 
    • OUR PLANETS In the order of their proximity to the sun         My – Mercury Very – Venus Elegant – Earth Mother – Mars Just – Jupiter Served – Saturn Us – Uranus Nuts – Neptune
    • THE SUN • The Sun is the star at the center of the Solar System • The Sun is composed primarily of the chemical elements hydrogen and helium; they account for 74.9% and 23.8% of the mass of the Sun in the photosphere. • It has a diameter of about 1,392,684 km around 109 times that of Earth, and its mass is approximately 330,000 times the mass of Earth.
    • THE SUN • • • The surface of the sun is called the photosphere. The photosphere is 340 miles thick and it's temperature s range from 5,500 °C to 6,000 °C. It has dark spots called sunspots which are the only solar activity observable by the naked eye. The source of the sun's fuel is hydrogen and helium gases. Through a special chemical reaction, called nuclear fusion, the hydrogen gas is "burned" releasing an enormous amount of energy in the form of light and heat.
    • MERCURY  Distance (From Sun) :- 58 Million Kms.  Revolution Motion :-88 Days.  Rotation Motion :- 59 Days.
    • VENUS • Distance (From Sun) :- 108 Million Kms. • Revolution Motion :- 255 Days • Rotation Motion :- 243 Days • It is also known as Morning Evening Star • It could be seen hour befoe Sun rise and after Sun st. • Twin sister of the Earth • Known as Red Planet
    • VENUS TRANSIT Image of the 2012 Transit taken by NASA's Solar Dynamics Observatory spacecraft
    • VENUS TRANSIT • A transit of Venus across  the Sun takes place when  the planet Venus passes directly  between the Sun and Earth (or  another planet), becoming visible  against (and hence obscuring a  small portion of) the solar disk. • During a transit, Venus can be seen  from Earth as a small black disk  moving across the face of the Sun.  The duration of such transits is  usually measured in hours (the  transit of 2012 lasted 6 hours and 40  minutes)
    • DIFFERNCE BETWEEN TRANSIT & ECLIPSE • Transit is the passage of a planet across the disk of the Sun - only transits of the inner planets Mercury and Venus are possible • A transit • An eclipse in when the moon passes in front of the Sun. • An eclipse totally hides what it is in front of. 
    • EARTH • Distance ( From the Sun) :- 150 Million Kms. • Revolution Motion :365 Days 5 Hours 48 Minutes 43 Seconds • Rotation Motion :-1 Day (24 Hours ) • Known as Blue Planet • Life is found .
    • EARTH
    • Revolution of the eaRth
    • eaRth -the Blue Planet • Equatorial Circumference :12756 Kms. • Polar Circumference :- 12714 Kms.
    • the Moon - the onlY Satellite of the eaRth
    • BiRth of the Moon
    • SYnChRoniZe Motion of Moon
    • the Moon - the onlY Satellite of the eaRth  Perigee Distance :- 3 Lakh 84 Thousand Kilometers.  Apogee Distance :- 4 Lakh 6 Thousand Kilometers.  Circumfernce is - 3476 Kilometers .  Highest mountain is Libnitus located at south pole.  Highest peak is 35000 ft.  Ratio of Gravity between moon to earth is 0.166  Revolution time of the moon around the earth is 27 Days 7 Hours 43 Minutes 11. 47 Seconds
    • RelationShiP BetWeen Moon & the eaRth A. Tides occurs due to the gravity pull of the moon B. Tides C. Lunar Eclipse occurs when sun earth and the moon comes in a straight line. D. Solar Eclipse occurs when sun the moon and the earth comes
    • tiDeS
    • tiDeS
    • MiSSion ChanDRaYan  THE WORD CHANDRAYAAN – 1 IS DERIVED FROM A SANSKRIT WORD LITEARLLY MEANING MOON VECHILE.  IT IS INDIA’S FIRST MISSION TO MOON DEVOLPED BY ISRO (INDIAN SPACE RESARCH ORGANISATION).  THE MISSION INCLUDES A LUNAR ORBITER AND AN IMPACTOR.  IT WAS LAUNCHED ON 22 OCTOBER 2008 WITH HELP OF A MODIFIED VERSION OF PSLV XL FROM SATISH DHAWAN SPACE CENTRE, SRIHARIKOTA, ANDHRA PRADESH AT 6:23 IST.  ESTIMATED COST - RS 386 CRORE (US$ 80 MILLION)
    • MiSSion ChanDRaYan  THE IDEA OF UNDERTAKING AN INDIAN SCIENTIFIC MISSION TO MOON WAS INITIALLY MOOTED IN A MEETING OF THE INDIAN ACADEMY OF SCIENCES IN 1999 THAT WAS FOLLOWED UP BY DISCUSSIONS IN THE ASTRONAUTICAL SOCIETY OF INDIA IN 2000.  A NATIONAL LUNAR MISSION TASK FORCE WAS CONSTITUTED BY THE INDIAN SPACE RESEARCH ORGANISATION (ISRO) PROVIDED AN ASSESSMENT ON THE FEASIBILITY OF AN INDIAN MISSION TO THE MOON AS WELL AS DWELT ON THE FOCUS OF SUCH A MISSION AND ITS POSSIBLE CONFIGURATION.
    • SPeCifiCation of ChanDRaYan  MASS:- 1380 KG AT LAUNCH, 675 KG AT LUNAR ORBIT, AND 523 KG AFTER RELEASING THE IMPACTOR.  DIMENSIONS: CUBOID IN SHAPE OF APPROXIMATELY 1.5M.  POWER:MAINLY POWERED BY ITS SOLAR ARRAY, WHICH INCLUDES ONE SOLAR PANEL COVERING A TOTAL AREA OF 2.15 X 1.8 M GENERATING 700 W OF POWER, STORED IN A 36 A-H LITHIUM-ION BATTERY.USES A BIPROPELLANT INTEGRATED PROPULSION SYSTEM.
    • SPeCifiCation of ChanDRaYan     IT HAS THREE SOLID STATE RECORDERS (SSRS) ONBOARD TO RECORD DATA FROM VARIOUS PAYLOADS. SSR-1 WILL STORE SCIENCE PAYLOAD DATA AND HAS CAPABILITY OF STORING 32GB DATA. SSR-2 WILL STORE SCIENCE PAYLOAD DATA ALONG WITH SPACECRAFT ATTITUDE INFORMATION (GYRO AND STAR SENSOR), SATELLITE HOUSE KEEPING AND OTHER AUXILIARY DATA. THE STORING CAPACITY OF SSR-2 IS 8GB. M3 (MOON MINERALOGY MAPPER) PAYLOAD HAS AN INDEPENDENT SSR WITH 10GB CAPACITY.
    • PaYloaD of ChanDRaYan
    • PaYloaDS of ChanDRaYan • THE SCIENTIFIC PAYLOAD HAS A TOTAL MASS OF 90 KG AND CONTAINS FIVE INDIAN AND SIX FOREIGN INSTRUMENTS . 1 2 3  INDIAN PAYLOADS 1.TERRAIN MAPPING CAMERA 2. HYPER SPECTRAL IMAGER 3.LUNAR LASER RANGING INSTRUMENT 4.HIGH ENERGY X-RAY PAYLOAD 5. MOON IMPACT PROBE
    • FIRST PICTURE SENT BY CHANDRAYAN
    • inDia’S SatelliteS SinCe inDePenDenCe • • Aryabhata was India's first satellite. It was launched by the Soviet Union  on 19 April 1975 from Kapustin  Yar using a Kosmos-3M launch  vehicle. •  It was built to conduct experiments  in X-ray astronomy, aeronomics, and  solar physics. The spacecraft was a  26-sided polygon 1.4 m in diameter. • The satellite reentered the Earth's  atmosphere on 11 February 1992.       It was 360kgs.
    • aRtifiCial Satellite-hoW Sent Shroud Protects the spacecraft Upper stage Orbit insertion rocket engines and propellant tanks Main vehicle Primary liquid or solid rocket propellant tanks Booster packs Solid strap-ons for some rockets to increase initial thrust Engine / nozzles Mechanism for combining propellants and focusing Step 7: Mechanical deployments Step 6: Satellite initial checkout Step 5: Orbit insertion Step 4: Shroud opening Step 3: Main engine cut-off and separation Step 2: Booster cut-off and separation Step 1: Ignition and launch
    • launCh SeQuenCe Step 1 AV North NORTH POLE Pole AV Step 2 Step 3 Launch into parking orbit (With orbit insertion burn) Minimum energy transfer Burn 1 to change path Burn 2 to change to higher orbit AV Orbit plane transfer (With vector thrust burn)
    • launCh funDaMentalS force = (mass) x (acceleration) f = (m)(a) The thrust of a launch vehicle must oppose gravity and atmospheric drag To get into orbit, a vehicle must achieve a velocity FORCE TIME FORCE & TIME & of FORCE 24 (24 times&the speed of sound)FUEL mach Thrust = Pounds or Kg Impulse = Pounds per sec = Newtons per sec Specific Impulse (Isp) Isp = Thrust (lb) fuel weight (lb) burned in
    • aRounD in oRBit V V NORTH POLE LAUNCH INTO PARKING ORBIT (WITH ORBIT INSERTION BURN ) ORBIT PLANE TRANSFER (WITH VECTOR THRUST BURN ) V2 NORTH POLE V1 HOHMANN (MINIMUM ENERGY) TRANSFER (BURN 1 TO CHANGE TO ELLIPTICAL ORBIT AND BURN 2 TO CHANGE TO NORTH POLE V2 V1 FAST TRANSFER (BURN 1 TO CHANGE TO LARGE ELLIPSE AND BURN 2 TO FORCE INTO NEW ORBIT)
    • STAGE OF LAUNCH VEHICLE • The technique, called staging, is used in all current launch vehicles. • There are two standard forms of staging: serial staging and parallel staging. • In serial staging the stages are stacked vertically in the rocket and are fired one after another. • Parallel staging uses stages strapped alongside each other which are fired simultaneously. • Most launch vehicle use both
    • LAUNCH TO GEOSTATIONAry OrbIT • It is normal for launch vehicles to have 3 stages, and for each stage to be dropped as its propellant is consumed. • The first stage uses a single powerful engine, the Vulcain. • Heavy lift rockets like the Ariane 5 have two or more solid rocket boosters (SRB) to help the launcher to lift heavier satellites • Both the main engine and SRB are ignited at lift off • The SRB are jettisoned about 2 minutes into the flight when their fuel is spent 
    • LAUNCH TO GEOSTATIONAry OrbIT • About 8 minutes into the flight the first stage has consumed all its fuel. • The first stage is jettisoned and the second stage engine ignites  • The payload is protected by an aerodynamic fairing inside the atmosphere. This is not needed when the rocket is in space so it is jettisoned 
    • LAUNCH TO GEOSTATIONAry OrbIT • About 25 minutes into the flight the seond stage has consumed all its fuel and is jetissoned  • The third stage is ignited. and burns until the correct velocity has been achieved. At this time it is shut down  • The satellite has enough speed to coast to 36000 km altitude, the highest point of the flight. • This highest point is called the apogee
    • LAUNCH TO GEOSTATIONAry OrbIT • The launch vehicle needs to accelerate the satellite to a horizontal velocity of 10.3 km/s at an altitude of about 500km. • This puts the satellite in an elliptical geostationary transfer orbit (GTO) • In this orbit the satellite will coast up to the geostationary orbit at 36,000 km altitude • Gravity slows the satellite until, at 36000 km, it is only travelling at 1.6 km/s
    • LAUNCH TO GEOSTATIONAry OrbIT • The satellite completes several orbits of the GTO while its electronic systems are powered up. • AT the highest point, called apogee, the satellite fires its own rocket motor, called the apogee boost motor ABM) • The ABM accelerates the satellite from 1.6 km/s to 3.1 km/s, putting the satellite into a circular orbit at 36000 km altitude. It is now in the geostationary orbit.
    • MArS • Distance from the Sun :- 228 Millions kms. • Its Atmosphere is very thin. • It has two Satellites:Diamos & Phobos. • Rotational Motion :24.64 Days. • Revolution Motion :687 Days.
    • MArS MISSION -INDIA
    • ASTErOID • Fragmented Mass of the Dead Planets lying between Mars and Jupiter is called Asteroids. • These also revolves around the Sun like a Planets. • But they do not have any atmosphere or life.
    • JUPITEr • Distance :- 778 Millions Kms. • Atmosphere is basically made up of Hydrogen and Helium . • The outer surface is made up of methane and Ammonium • Total number of Satellites :- 28 • Faint Ring surrounds the Jupiter • So big that 1300 Earth sized planets could be
    • FOUr bIG SATELLITES OF JUPITEr • • • • Io Europa. Ganymede Calisto
    • SATUrN • This Planet is located two times farthest the Distance between Jupiter and the Sun i.e. 1,427 Million Kms. • With the help of Binoculars one could see the Three Distinct Rings of Saturn. • Revolution Motion :29Years 5 Months • Rotation Motion :- 10 Hrs 40 Minutes
    • FIVE SATELLITES OF SATURN TITAN MIMAS DIONE TETHYS RHEA
    • UrANUS (ArUN) • Harshel discovered this Planet in 1781 A.D. • Atmosphere is primarily composed of Hydrogen and Helium. • Distance from the sun :- 2,869 Million Kms. • Extremely cold Atmospheres • Revolution Motion :-84 years. • Rotation Motion :- 17 Hrs. 14 Min • Numbers of Satellites :- 17 • Uranus has an axial tilt of 97.77°, so its axis of rotation
    • SATELLITES OF UrANUS
    • NEPTUNE (VArUN) • This Planet was discovered by Urbain Le Verrier in 1946. • Distance ( From Sun) :- 4496 Million kms.  Revolution Motion :- 164 years. • Atmosphere is Composed of 79 % Hydrogen 18 % Helium and 3 % Methane. • That’s Why this Planet looks
    • SATELLITE OF NEPTUNE
    • METEOrITES & METEOrS • Small pieces of • When meteoroids space debris usually enter the Earth's parts of comets or atmosphere they are asteroids)that are called meteors. on a collision course with the Earth are called meteoroids.
    • WHy DO METEOrS HAVE A STrEAk OF LIGHT?? • As they travel through our atmosphere, meteors collide with air molecules that knock away materials and strip electrons from the meteor… • When the stripped atoms recapture electrons, light is emitted… • The color of the light depends on the temperature and the material being “excited.”
    • ArE ALL METEOrS THE SAME COLOr?? • The material or element that makes up a meteor is the main factor that determines the color of its glowing trail… - Sodium = orange-yellow - Iron = yellow - Magnesium = blue-green - Calcium = violet - Silicon = red
    • SPOrADIC METEOrS • These are the meteors that can be seen on any given night • They are not associated with any particular meteor shower • They come from random directions in the sky
    • COMET • A comet is an icy small Solar System body that, when passing close to the Sun, heats up and begins to outgas. • Comet nuclei range from a few hundred metres to tens of kilometres across and are composed of loose collections of ice, dust, and small rocky particles. • The coma and tail are much larger, and if sufficiently bright may be seen from the Earth without the aid of a telescope. • Halley's Comet is short-period comets and is visible from Earth every 75–76 year
    • FAMOUS COMETS S.NO. NAME OF THE COMET YEAR OF OCCURANCE FIRST DISCOVERED IN THE YEAR 1 COMET HALLEY 76.3 1066 2 GREAT COMET OF 1811 3000 1811 4 COMET MRKOS 5.3 1957 5 COMET KOHOUTEK 75000 1973 6 7 WACHMANN HOLMES’ COMET 16.2 7.0 1925 1889
    • THANkS yOU