Stars and the solar system

This Power point presentation is about Solar System discussing about the Sun, different Planets, Comets, Asteroids, Meteoroids, Meteors, Meteorites. General introduction to each of the mentioned topic is given in easiest and simplest way possible so that everyone can understand it easily. This presentation is specially for CBSE students of Class 8th

1. STARS AND THE SOLAR SYSTEM CLASS 8 SCIENCE PREPARED BY- BHAVYA VASHISHT

2. CELESTIAL OBJECTS The objects which exist in the sky (or in outer space) Includes Stars, Planets, Satellites, Asteroids, Comets, Meteoroids, meteors, meteorites Also called Heavenly objects/ Heavenly bodies

3. STARS PLANETS ASTEROID COMET SATELLITE (MOON) METEOROID

4. THE NIGHT SKY Various celestial objects which can be seen easily in the night sky are stars, planets, moon and meteors (shooting stars) An important characteristic of stars is that they appear to twinkle in the sky. This is an illusion caused by disturbance of star’s light by Earth’s atmosphere. Planets do not twinkle NIGHT SKY

5. STARS Celestial objects (like the Sun) that are extremely hot and have light of their own Emit heat and light continuously Consists mostly of Hydrogen gas Heat and light produced by nuclear fusion by which Hydrogen converts into Helium Very large in size but appears small because they are very far Sun is a star, which rises in East and sets in the west. This is due to rotation of Earth from West to East

6. POLE STAR Appears to be stationary It lies on the axis of rotation of Earth which is fixed in space and doesn’t change with time. POLE STAR LIES ON AXIS OF ROTATION

7. UNIT OF MEASURING DISTANCE Expressed as Light Year Light year is distance travelled by light in One year Calculated by multiplying speed of light with number of seconds in a year Speed of Light= 3,00,000 Km/s Number of seconds in a year= 3,15,36,000 seconds 1 light year = 9,460,800,000,000 kilometres 9.46 X 10 12 kilometres

8. Light Minute Distance travelled by light in 1 minute Distance between Sun and Earth= 150,000,000 km Distance of Earth from Sun is 8 light minutes Second nearest Star= Proxima Centauri It is 4.3 light years away

9. CONSTELLATIONS Group of stars which appears to form some recognizable shape or pattern About 88 constellations are present Named by signifying an animal, a human being or some other object which it appears to resemble. Move in sky from East to West Consists of a group a large number of stars, some of which are bright and can be seen easily with naked eye whereas others are dim and seen with difficulty For describing, only bright stars are considered

10. URSA MAJOR CONSTELLATION Also called Great Bear, Big Bear, Big Dipper, Plough, Satparishi Group of many stars but 7 are bright and easily visible Visible during Summer season in early part of night We can locate pole star with its help It appears to revolve around pole star BIG DIPPER/ PLOUGH GREAT BEAR/ BIG BEAR

11. LOCATING POLE STAR IN NIGHT SKY WITH HELP OF URSA MAJOR CONSTELLATION URSA MAJOR CONSTELLATION REVELOVES AROUND THE POLE STAR Locating pole star

12. ORION CONSTELLATION Also called as Hunter, Mriga Consists of 7 or 8 bright stars and several faint stars Visible in sky during winter season in late evenings Brightest star ‘Sirius’ loacted close to Orion Constellation ORION CONSTELLATION LOCATING SIRIUS WITH HELP OF ORION CONSTELLATION

13. CASSIOPEIA CONSTELLATION Consists of 5 stars Arranged to form distorted ‘W’ or ‘M’ Visible during winter in early part of night CASSIOPEIA CONSTELLATION

14. LEO MAJOR CONSTELLATION Consists of 9 main stars Thought to form the outline of a big lion Visble during summer in early part of night LEO CONSTELLATION

15. THE SOLAR SYSTEM Consists of Sun, the Eight Planets, their Satellites (Moon), Asteroids, Comets and Meteoroids Planets from the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune Sun is at the centre and all objects revolves around it in fixed paths called orbits Satellites revolve around the planet Asteroids revolve around sun between orbits of Mars and Jupiter Comets and meteoroids are minor members and revolve around the Sun Sun is biggest object, have very powerful gravitational force Gravitational force keeps solar system together and control movement of planets and other members of solar system

16. THE SOLAR SYSTEM

17. SUN ( SURYA ) It’s a medium sized star with average brightness Appears bigger as close to Earth Diameter is 100 times more than earth, mass million times more Surface temperatures is around 6000 °C Consists mostly of hydrogen gas Nuclear fusion reactions power the Sun Main source of heat and light energy for all the planets and satellites Planets and other objects in the sky reflect part of sunlight falling on them due to which they shine and become visible to us.

18. Planets (GRAHA) Large celestial objects revolving around the Sun in closed elliptical paths called orbits Planets from the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune Have no light of their own Do not twinkle like stars Move around Sun from West to East Their position changes with respect to stars Very small as compared to Sun Mercury, Venus, Mars, Jupiter, Saturn can be seen by naked eye Made up of Rock and Metal, or gas 4 inner planets made up of Rock and have metallic core Comparatively small in size and have dense bodies having solid surface

19. Planets ( graha ) Outer planets mainly made of Hydrogen and Helium Do not have solid surface Have rings around them Have large number of natural satellites around them All planets rotate on their axis and also revolves around the sun Period of revolution- Time taken by planet to make 1 revolution around the Sun. Period of rotation- Time taken by a planet to complete one rotation on its axis Till 2006 there were 9 planets, 9 th planet being Pluto. In 2006, International Astronomical Union (IAU) adopted new definition of planet, Pluto didn’t fit this definition, hence it was excluded

20. Mercury ( Budh Graha ) Nearest to the Sun Smallest planet Very hot in the day Has rocky surface covered with craters Usually hidden by Sun’s glare Visible just before sunlight or just after sunset near horizon Called Morning Star/ Evening Star Show phases like moon. As it lies inside Earth’s orbit, its sun lit surface is visible in varying amounts from the Earth. N o life exist on it Has no Satellite (Moon)

21. venus ( shukra Graha ) Second planet from the Sun, closest to Earth Rotates from East to West, so Sun rise in West and sets in East Rocky planet Dense atmosphere consisting almost entirely CO2 Brightest object in night sky (except for Moon) Very bright because its cloudy atmosphere reflects 75% sun light Called Morning Star/ Evening Star Hottest planet N o life exist on it Has no Satellite (Moon) Show phases like moon

22. earth ( prithvi Graha ) Third planet from the Sun Spherical in shape Appears blue and green from space Only planet in Solar System that supports life. Reasons for life on Earth: Distance from Sun(temperature) Size of Earth (gravity) Environmental factors responsible for life: Has an atmosphere Has large quantities of water Suitable temperature range Protective blanket of Ozone

23. earth ( prithvi Graha ) Rotates on an imaginary axis passing through north and south poles Completes 1 rotation in 24 hours which we call 1 day Rotates from West to East Axis of rotation slightly tilted with respect to plane of orbit around Sun Axial tilt= 23.5 degrees Rotation of Earth causes Day and Night Takes 1 year to complete 1 revolution around Sun Motion of tilted Earth around Sun causes seasons Earth has 1 Satellite called Moon

24. mars ( mangal Graha ) 4 th planet from the Sun Also called Red Planet because its surface appears red Small in size and is rocky planet Most similar to Earth Has thin atmosphere containing mainly CO2 with small amounts of Nitrogen, O2, noble gases and water vapor Atmosphere could be enough to support primitive forms of life No evidence of any life found yet Mars has 2 Satellites (Moons)

25. jupiter ( brihaspati Graha ) 5 th planet from the Sun Biggest planet of the Solar system Diameter is 11 times that of earth, mass about 318 times Almost 1300 Earths can be placed inside Jupiter Appears very bright in night sky 1 st gas planet made up mainly of Hydrogen and Helium Also has poisonous gases like Methane and Ammonia Very cold planet Has no solid surface Has faint rings around it Jupiter has 67 Satellites (Moons)

26. saturn ( shani Graha ) 6 th planet from the Sun 2 nd Biggest planet of the Solar system Made up mainly of Hydrogen and Helium Least dense planet (density less than water) Very cold planet Only planet with well developed rings encircling it 3 distinct sets of ring visible Saturn has 62 Satellites (Moons)

27. uranus ( indra Graha ) 7 th planet from the Sun 1 st planet to be discovered with help of telescope 3 rd largest planet Rotates from East to West like Venus Highly tilted axis Appears to roll on its side while O rbiting the Sun M ade up mainly of Hydrogen and Helium Also has poisonous gases Very cold planet Has faint rings around it Uranus has 27 Satellites (Moons)

28. neptune ( varun Graha ) 8 th planet from the Sun Outermost planet of Solar System 2 nd planet to be discovered with help of telescope Looks like blue green speck M ade up of frozen Hydrogen and Helium Has faint rings around it Extremely cold N eptune has 14 Satellites (Moons)

29. Satellites Celestial body that revolves around a planet Moon is natural satellite of Earth Mercury and Venus don’t have satellites Satellites revolve around planets due to gravitational pull of the planets Have no light of their own Shine and become visible as they reflect Sunlight falling on it PLANE T SATELLITE

30. MOON Natural satellite of Earth Revolves around Earth on definite path Gravitational attraction of Earth holds Moon in its orbit Size 1/4 th the size of Earth diameter, Mass 1/8 th Distance from Earth= 3,84,000 km (Closest celestial object to Earth) Surface covered with hard and loose dirt and has craters of different size Has steep and high mountains No air or water on Moon, so no life Extremely hot days and cold nights First Man landed on Moon in July 1969 was Neil Armstrong followed by Edwin Aldrin

31. moon We see moon because it reflects sunlight falling on it We only see that part which reflects sunlight, we don’t see other part Moon always show same face to Earth as it rotates This is because it completes 1 rotation on its axis in same time which it takes to complete 1 revolution around Earth Phases of Moon : different shapes of bright, visible part of the Moon as seen from Earth during whole month. Moon revolves around the Earth once every month and moves around the Sun along with Earth, different amount of its sun-lit surface are turned towards the Earth leading to change in the appearance of Moon and formation of phases of Moon The night when Moon isn’t visible = New Moon ( Amavasya ) The night on which the whole bright disc of Moon is visible= Full Moon ( Poornima )

32. Phases of MOON

33. asteroids Small celestial objects which revolve around the Sun between orbits of Mars and Jupiter Called as Minor Planets Made up of rocks Biggest are hundreds of kilometres in diameter, smallest only hundreds of meters Can only be seen through large telescopes Formed at same time as rest of the planets which somehow couldn’t assemble to form major planet Sometimes they collide with one another, break into pieces and form meteoroids which gives rise to meteors (shooting stars) or meteorites

34. comets Very s mall celestial objects made up of gas and dust which revolve around the Sun in highly elliptical orbits and become visible only when they come close to the Sun. As it approaches the Sun, it develops a long, glowing tail Comet is a collection of Gas and dust which appears as a bright ball of light in the sky with a long glowing tail millions of kilometres long Period of revolution around sun is very large Halley’s comet has a period of revolution of about 76 years

35. Meteoroids: meteors and meteorites C elestial objects ranging in size from a tiny sand grain to big boulders of several hundred tonnes and revolve around the Sun in their orbits Mainly left behind by disintegration of Asteroids and Comets Much smaller in size than asteroids and comets When due to some reason, a meteoroid breaks away from its orbit around the Sun and falls towards Earth, it becomes a meteor. Meteors are celestial bodies from the sky which we see as bright streak of light that flashes for a moment across sky. Meteors are also called as shooting stars because when viewed from Earth, it looks like a streak of starlight shooting across the sky. Meteors have no light of their own. A meteor which doesn’t burn up completely on entering th e Earth’s atmosphere and lands on Earth is known as Meteorite.

36. Artificial satellites A man made space-craft placed in orbit around the Earth with help of a launch vehicle called Rocket Rockets carry artificial satellite from the Earth to a height of few hundred kilometres and gives it a sideways push making satellite move in an orbit around Earth. Motion of artificial satellite around Earth is maintained by gravitational pull of the Earth. Artificial satellites carry large variety of equipment and instruments inside them. Electricity required for running the equipment in artificial satellite is provided by solar cells. Remote Sensing: Technique of collecting information about an object from a distance without making a physical contact. Remote sensing satellites scan Earth

37. Artificial satellites

38. Artificial satellites Uses Used for communicating such as long distance transmission of television programs, radio programs, telephone calls and internet Used for weather forecasting and for giving warning of floods etc Used for surveying natural resources of Earth like Minerals, agricultural crops, potential fishing zones etc Used for spying for military purposes Used to collect information about other planets , stars, galaxies, etc First Indian Satellite was launched in 1975 called Aryabhatta Other Indian Satellites : Bhaskara , INSAT, IRS, EDUSAT, Kalpana-1 etc INSAT= Indian National Satellite EDUSAT= Education Satellite IRS= Indian Remote sensing Satellite Agency for Indian space science programmes : ISRO ISRO= Indian Space Research Organisation

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