SOLAR SYSTEM

SOLAR SYSTEM

•      The solar system comprises of the sun and eight planets revolving round the sun, many satellites revolving around their respective planets, thousands of comets and billions of meteoroids.


•      Planets (in the increasing order of their distance from the Sun)

1.       Mercury
2.      Venus
3.      Earth
4.      Mars
5.      Jupiter
6.      Saturn
7.      Uranus
8.      Neptune

•      Sun is the centre of the solar system.


•      Sun is the largest body of the solar system.


•      Planets have no light of their own.


•      Planets revolve around the sun from West to East.


•      Planets rotate upon their axis from West to East, except Venus and Uranus which rotate upon their axis from East to West.


•      Mercury and Venus have no satellites.


•      Earth has only one satellite (the moon).


•      Jupiter has more than 60 satellites.


•      Asteroids (or) Planetoids – a series of very small planets or fragments of planets revolving around the sun between the orbits of Mars and Jupiter.


•      The average distance of the sun from earth is about 150,000,000kms.


•      Earth is the third nearest planet to the sun.


•      Venus is the nearest planet to the earth.


•      Mercury and Venus are called inferior planets.


•      All planets which are at a greater distance from the sun than the earth are called superior planets.


•      Mercury, Venus, Earth and Mars are called inner planets.


•      Jupiter, Saturn, Uranus and Neptune are called outer planets.


•      Venus the brightest planet.


•      Mercury is the smallest planet.


•      Jupiter is the largest planet.


•      Mars is called the red planet.


•      Earth is called the living planet or the blue planet.


•      Pluto was previously considered as a planet.


•      The International Astronomical Union evolved a precise definition of a planet in 2006. According to this new definition, a planet is a celestial body that

1. is in orbit around the sun.


2. has sufficient mass for its self gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round shape).


3. has cleared the neighbourhood around its orbit.

•      The orbit of Pluto is most elliptical and as a result, it intersects the orbit of Neptune. Therefore, in its journey around the sun, Pluto comes closer to the sun than Neptune for some years.


•      Because of this, the International Astronomical Union excluded Pluto from the category of Planets and has named it a Dwarf Planet.