TNPSC - Geography - 11th Standard Text Books

1.  System introduced by a Russian mineralogist, Vladimir Vernadsky, in the year 1920s
2. The Earth has two motions. It rotates on its axis, inclined at an angle of 23 ½0
3. Earth is considered a unique subsystem in the planetary system.
4. The lithosphere, hydrosphere and atmosphere are the abiotic components of the Earth 
5. The planetary system consists of Eight planets : Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and about 90 satellites.
6. Mercury, Venus, Earth, and Mars are smaller in size -  these planets are called rocky planets.
7. Jupiter, Saturn, Uranus and Neptune are bigger in size. They have small amounts of rocks and large amounts of gases, and are called Gaseous Planets.
8. The Sun is the main source of energy for the planetary system.
9. The Sun consists of 92% hydrogen, 7.8% helium and 0.2% other gases. 
10. The temperature on the surface of the Sun is 6,000 degrees Celsius and the temperature at the center of the Sun is more than 15,000,000 degree Celsius
11. The Sun shines as a consequence of the fusion of hydrogen into helium, which is constantly taking place in its core. Hence, astronomers call the Sun a “Big Fire Ball”
12. Scientists believe that the Sun will cease its function when the hydrogen is exhausted. It can burn for another 5,000 million years. 
13. It is estimated that the Sun had enough hydrogen to burn for 10,000 million years.
14. Our Solar System is part of one such galaxy known as the Milky Way.