The Earth in The solar System

1. The Earth in The solar System • Have you seen the night sky? • How does it look & What all objects do you see? • Have you seen twinkling stars, the Sun, the Moon ? • Then what about day time? • Does the sky differ during day time?

2. Where do these star vanish away during day light? • During day time it is the bright light of the sun that does not allow us to see the stars. All of these stars are hidden • The Sun, the moon and all those objects shining in the sky are called Celestial Bodies .

3. Celestial Bodies • The Sun, the moon and all those objects shining in the night sky are called Celestial Bodies. • Some are very big and hot. • Made of gases

4. Stars • Made of gases • Have their own heat and light, which they emit in large amounts. • The celestial bodies which emit their own heat and light are called stars. • The sun is one such star. • A star is born when it is in Nebula State and it stops giving light when it reaches the Super Nova State.

5. Constellations • Some stars make up groups and form definite patterns know as constellations. • Such groups can be recognised by the shapes they form. • Eg. Ursa Major or Big Bear, Small Bear or SaptaRishi, Orion the hunter etc. • All Zodiac Signs are based on constellations like Leo, Libra, Sagittarius, Capricorn etc. • There are in all 88 constellations

6. A Star of it’s Kind • Among the cluster of stars there is one star which is distinctly seen in the night sky. • It is almost above the North Pole and always shows the North direction. • So it is known as the Pole Star Or North Star or Polaris. • In Ancient times when there was no compass people at night use to find their way by looking at the Pole Star • We can locate it with the help of Pointers in SaptaRishithat always point at the Pole Star

7. Planets • Celestial Bodies which do not have their own heat and light but are lit up by the light of the sun are called Planets. • Derived from a Greek word ‘Palentai’ meaning wanderers • Planets have their own Satellites known as moons • They move around the sun in an Orbit or a fixed path also known as an elliptical path.

8. Satellite of Earth • Moon is the Natural Satellite of the Earth • It moves around the Earth as well as the sun • Do we see the same shape and position of Moon daily? • It varies due to the light of the Sun and position of the moon • we get two important days Full Moon Night and New Moon Night

9. Full Moon Night • When we see the Full Moon • The moon is far away from sun • Sunlight is fully reflected making it clearly visible to the naked eye • It is also known as Poornima • Poornimaor Full Moon appears once a month • According to the Hindu Lunar Calendar on the 15th day of each month

10. New Moon Night • When No Moon is seen in the sky • The moon is between the sun and the earth making it barely visible as light of the sun is not reflected • It is also known as Amavasya • Amavasya or New Moon Night appears once in a month • According to the Hindu Lunar Calendar the last day of each month. • After New Moon Night the next day new month begins

11. The Solar System • The word Solar has been derived from a Roman word ‘Sol’ meaning ‘The Sun God’ • The solar system consists of the sun, the moon, stars, planets, asteroids, meteoroids. • All of these celestial bodies move around the Sun • So it is also known as the Solar Family with Sun as its head

12. The Sun • The sun is the head of the solar system • It is in the centre of the solar system • It is a huge ball of fire • Made up of hot gases • It provides the pulling force that binds the solar system • It is the ultimate source of heat and light for the solar system

13. But this tremendous heat is not felt on Earth by us because it is far away from us • Though it is the closest star to the earth in yet it is 150 million km away from earth • Also the earth’s atmosphere protects us from the harmful sun rays known as (UV) rays

14. Planets • There are 8 planets in the solar system • Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune • There are four inner planets and four outer planets • These are divided by an asteroid belt

15. Inner Planets • These are Mercury, Venus, Earth and Mars • These are nearer to the sun • Are known as rocky planets as made of rocks • Due to sun’s heat the gases and water on these planets are boiled making them rocky planets • These planets are small in size as compared to the outer planets

16. Outer Planets • These planets are Jupiter, Saturn, Uranus and Neptune • These planets are large in size • These are far away from the sun compared to the inner planets • So theses are made up of gases • Jupiter, Saturn and Uranus have rings around them

17. The Earth • Is the third nearest planet to the sun • It is the fifth largest in the solar system • It is slightly flattened at the poles and bluged at the centre. • This shape is described to be Geoid. • Geoid means Earth like

18. Earth a Unique Planet • There are favourable conditions on earth to support life • It is neither too cold nor too hot • It has water and air very essential for life • Air contains life-supporting gases like oxygen • Two-third of earth is covered with water • Making it appear blue from outer space • So earth is also known as a Blue Planet

19. The Moon • Earth’s only natural satellite • It is one-quarter of the earth • As it is near to the earth it looks big • It is 3,84,400 km away from the earth • It moves around the earth • It takes 27 days to complete one circle around the earth • We can not live on the moon • As there is no water or air • It has mountains, plains and depressions on its surface

20. Natural Satellite • Naturally exists in space • Orbits around the planet • Cannot be controlled • We cannot communicate with it • It moves according to the law of nature • It can be an object of study Eg moon

21. Artificial/Man-made Satellite • It is designed by scientists • It is launched in space • It is controlled by us • We can communicate with it by sending signals and receiving messages • It is programmed and moves accordingly • It is an instrument to study planets and other celestial bodies in the space EgAryabhatta

22. Asteroids • Asteroids move between the orbits of Mars and Jupiter, there are thousands of planets like small bodies revolving around the sun along with planets. • Are large in size • Are called minor planets • These are made up of stone or metal

23. Meteoroids • Meteoroids are small pieces of rock and dust which revolve around the sun. • Are small in size • These are the size of a pea or 1 dust particle • Move around randomly in space • made up of rocks and debris of comets

24. Meteor and Meteorite • Sometimes meteoroids enter the atmosphere, they start burning and become luminous. • They are commonly called shooting stars or meteors • The unburnt part of a meteor that falls on the earth is called a meteorite • They are made up of iron or stone or both

25. Universe • Universe is an unimaginable expanse of dust, gases, cloud, stars galaxies and life.

26. Galaxy • A family of billions of stars, clouds of dust and gases in the sky is called a Galaxy

27. Milky Way • The galaxy in which we live is called the ‘Milky Way’ or AkashGanga • Because it looks like splash of milk in the sky. • It is also a white band of millions of cluster of stars it was imagined to be a river of light flowing in the sky