The sun and the celestial bodies which revolve around it form the Solar system.
These celestial objects orbit around the sun due to the gravitational attraction between the sun and the objects. The sun, being the largest mass object in the system attracts the other objects, which are of smaller mass compared to the sun.
What is a Planet?
A Planet is any relatively large natural body that revolves in a fixed circular orbit around the sun or around some other star. It does not emit any light of its own.
What is a Period of Revolution?
The time taken for a planet to complete one revolution around the sun is called its Period of revolution.
The more distant a planet is from the sun, more will be the period of revolution.
What is a Period of Rotation?
The time taken for a planet to complete one rotation around its own axis is called its Period of rotation.
Planets in the Solar System
There are officially eight planets in the solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
Until 2006 there were 9 planets in the solar system. But the International Astronomical Union decided to call Pluto a ‘dwarf planet’ reducing the list of ‘real planets’ to 8.
Just like the earth, most planets in the solar system have their own moon, except some have more than one.
What is a Satellite?
A satellite is a celestial body revolving around another celestial body.
The moon revolves around the earth, so it is the earth’s satellite. Similarly, the earth
revolves around the sun. So, the earth is a satellite to the sun.
Summary
| The Solar System | The sun and the celestial bodies which revolve around it |
| Planet | A Planet is any relatively large natural body that revolves in a fixed circular orbit around the sun or around some other star. It does not emit any light of its own. |
| Period of Revolution | The time taken for a planet to complete one revolution around the sun |
| Period of Rotation | The time taken for a planet to complete one rotation around its own axis |
| Planets in the Solar System | Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune |
| Satellite | A celestial body revolving around another celestial body |
Did you know?
Though our planetary system is the only one officially called ‘solar system’, astronomers have discovered more than 2,500 other stars with planets orbiting them in our galaxy.
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