Geography:Important Points about our Solar system

• The sun, eight planets, satellites some other celestial bodies known as asteroids and meteoroids form the solar system. We often call it a Solar Family with the sun as its head.
• The Sun is the center of solar system. It is huge and made of extremely hot gases. It provides the pulling force that binds the Solar System.
• The eight planets in the Solar System are Mercury, Venus, Earth, Mars Jupiter Saturn, Uranus & Neptune.
• All the planets of the Solar System move around the Sun in an elongated fixed path called orbits.
• The Sun consists of 70% hydrogen, 28% Helium & 2% other gases .Its temperature is about 6000 °c & it is about 150 millions Kms away from the earth.
• The Sun’s light takes about 8 mins to reach earth. There are many theories that describe the evolution of the solar system. The most important and popular ones are

1. Gaseous Hypothesis
2. Nebular Theory
3. Tidal Hypothesis
4. Planetesimal Hypothesis
5. Binary- Sterr Hypothesis

The planets can be divided into two groups

a) Terrestrial Planets – Mercury, Venus earth & Mars

b) Jovian or Outer planets – Jupiter, Saturn Uranus, Neptune.

Stars:  Celestial bodies that are big hot & made of gases., have their own light and heat.

Constellation: Various patterns formed by different groups of stars are called constellation. Big bear is an example.

Satellite: Is a celestial body that moves around the planets.

Moon is the only satellite of the Earth. Its diameter is one quarter that of earth. It is about 3,84,4000 km away from the earth. It takes about 27 days to revolve around the earth and about the same time to rotate and its own axis. As a result only one side of the moon is visible to us on the earth .It does not have any favorable conditions like air or water for life.

Note: Neil Armstrong was the first man to land a moon’s surface, on July 29, 1969.

Asteroids: They are tiny bodies that move around the Sun., found between the orbits of Mars &Jupiter.

Meteoroids: These are small rock pieces that move around the Sun

Galaxy: It is a huge system of billions of stars and clouds of dust and gases. Millions of such galaxies make up the universe. Our solar system is a part of Milky Way Galaxy.

IMPORTANT FACTS

Largest-/ Biggest Planet          Jupiter

Smallest Planet                          Mercury

Satellites of Earth                      Moon

Nearest planet to the Sun        Mercury

Earth’s twin                                 Venus

Brightest Planet                          Venus

Brightest Star                              Ceres

Planets with rings around        Saturn

Red Planet                                   Mars

Blue Planet                                 Earth

Green Planet                               Neptune