Sun is one of the billions of stars in the sky. It forms the nucleus of the Solar System. All planets revolve around the Sun in elliptical orbits. It looks bright and big because of its nearness to the Earth than the other stars. It is at a distance of 150 million kilometres from the earth. Its diameter is 13, 92,000 km, compared to the Earth’s diameter of 12,756 km. Its volume is approximately 1.3 million times more than that of the Earth. Even though it is gaseous, it weighs more than 300,000 times as much as the earth. It takes 8 minutes 20 seconds for its rays to reach the Earth.

           Like other heavenly bodies, the Sun also is not static. It, along with its family of nine planets, revolves round the Milky Way and takes about 225 million years to complete one revolution. It also rotates on its own axis. The temperature at its centre is approximately 15 million degree centigrade. The solar surface is composed of three gaseous layers. The inner most layers are called ‘photosphere’. Its temperature is 6000° C. The solar spots are seen on this very layer. The next layer is ‘chromospheres’ which is approximately 14,000 km thick. This is composed of hydrogen, helium and other gases. The temperature of this layer is about 5000° C. The outer layer of the Sun is called ‘corona’.

               The Sun not only gives light to the Earth, but also gives life to its inhabitants. The Sun is the biggest source of heat and energy. Without it, there is, of course, no question of life on the Earth.