THE SOLAR SYSTEM

The sun is a medium size star in the Milky Way galaxy. There are million of galaxies in the universe. The universe is indeed very vast in size.
The solar system refers to the heavily bodies which belong to the sun's family. These heavily bodies are held in their places by the gravitational force of the sun. The sun is the source of light and radiant energy for all the heavily bodies of the solar system. The solar system consists of nine planets and their satellites, asteroids, comets and meteors. The planets rotate around their axes and revolve around the sun. The path along which each planet revolves around the sun is called its orbit.

The Sun

The sun is a hot gaseous body of large size. It has radius of about 700000 Km. the surface temperature of the sun is about 6000oc. In the core of the sun, the temperature is estimated to be about 20,000, 000oc. Such extremely high temperatures are produced by the conversion of hydrogen into helium by the process of fusion.

The Planets

There are nine planets in the solar system. The word planet means wanderer, as they seemed to move about or wander in the sky.

Date about planets

planets
Revolution Period
Rotation Period
Number of Satellites
Mercury
87days 14h 24m
59days
0
Venus
222 days 15h 36m
243 days
0
Earth
365 days
23 h 56m
1
Mars
686 days 4h 48m
24 h 37 m
2
Jupiter
11.86 years
9 h 50 m
16
Saturn
29.46 years
10 h14m
20
Uranus
84.01 years
10 h 49m
15
Neptune
164.79 years
18 h 24m
2
Pluto
247.69 years
6.3days
1





Satellites

Satellites are small bodies, which rotate on their    axes and revolve round the planets. Satellites are opaque bodies like the planets, shining by reflected sunlight falling on them. Titan, the largest satellite of Saturn has an atmosphere around it.

Comets

Comets are small bodies with a core dust and frozen gases. There are two kinds of comets. Periodical comets are those which have regular orbits around the sun and appear at fixed intervals. Hale's comet is a periodical comet. It is seen at intervals of 76 years.

The Earth

The earth is the third planet in terms of its distance from the sun. The earth lies between the orbits of Venus and Mars. The average distance of the Earth from the sun is about 150 million-km. The Earth is located at an optimum distance from the sun and hence it is neither too hot like Venus or Mercury nor too cold like Jupiter and other outer planets. The Earth is unique in that it has an atmosphere, which is rich in oxygen. Though other planets have an atmosphere, they do not contain much oxygen. The presence of oxygen has made life possible on the Earth. The atmosphere acts as a protective blanket around the Earth. The ozone .layer in the atmosphere absorbs the harmful ultra- violet the terrestrial radiation and keeps he earth warm during the nights and winter.

The shape of the earth is not exactly a sphere. There is a slight bulging at the equator and a flattening at the two Polar Reigns. This is caused by the rotation of the earth. That is why the equatorial diameter of the Earth (12,76 km) is larger than the Polar diameter (12,717 km).

The distance between the sun and the Earth is 148800000 km. The Earth takes 365 days and 6 hours to go round the sun. The Earth has only one satellite called Moon. The distance between the Earth and the Moon is 400000 km. The Moon takes 29 days and around the Earth.