All the planets in the solar system are bound to each other by gravity. But the question is how old is the solar system? The age of the solar system is 4.571 billion years. This system consists of the sun, the eight planets and their satellites, and thousands of other smaller heavenly bodies such as asteroids, comets, and meteors.
The Solar System
- This system is dominated by the sun which accounts for nearly 99.9% of the matter in the whole solar system.
- The size of the solar system is estimated to be about 100000 A.U.
- Planets Revolve around the sun in an oval-shaped orbit.
- The gravitational force of the sun keeps all the planets revolving around it.
- The sun is the source of all the energy in the solar system.
Members of the Solar System
The Sun
- The Sun is the nearest star to the Earth.
- It comprises 71% hydrogen, 26.5% helium, and 2.5% other elements.
- Hydrogen and Helium are the main gasses present in the Sun.
- The Sun’s diameter is 14 lakh km.
- Its size is 13 lakh times that of the Earth.
- It is the nearest to the Earth.
- Within the Sun, hydrogen is converted to helium due to nuclear fusion releasing tremendous heat and light.
- It takes about 8.5 minutes for light to reach Earth from the Sun.
- The distance between the sun and earth is 150 million km.
- The Shining Surface of the sun is called the photosphere, it appears like a disc, radiating energy and acts as a source of energy.
- The temperature at the center is around 15,000,000℃.
The Planets
- There are eight planets in the this system.
- A ninth planet has been discovered by NASA named Carla.
- The Planets are opaque bodies that continuously revolve around and are lighted by the Sun.
- The sequence of planets according to their size (in descending order) is Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars, Mercury.
- Jupiter is the biggest and mercury is the smallest planet in our solar system.
Classification of Planets
- The eight planets have been divided into two groups. All the planets of a particular group have some common features. ‘Terrestrial planets or Rocky planets and ‘Jovian planets or Gaseous planets’ are the two groups of planets.
- Mercury, Venus, Earth and Mars are called terrestrial planets.
- Jupiter, Saturn, Uranus and Neptune are called Jovian planets.
- Planets are classified into the following two groups: inner and outer planets.
Difference between inner and outer planets
| Inner Planets | Outer Planets |
| They are nearer to sun | Far away from sun |
| They Include Mercury, Venus Earth, Mars | They Include Jupiter, Saturn, Uranus, Neptune |
| They have thin, rocket crust | They all are gaseous bodies |
| They move faster and have a shorter period of revolution | They move slowly and have a longer period of revolution |
| They are made up of dense metallic minerals like iron, magnesium | They are made up of hot gasses like hydrogen and helium |
