The Sun is a large hot gaseous body. It is 1.3 million times bigger than Earth. The surface temperature of the Sun is about 6000°C. In the core of the Sun, the temperature is estimated to be about 20,000,000°C. Such extremely high temperature is produced by the conversion of hydrogen into helium by the process of fusion. This process releases tremendous amounts of energy and Sim radiates the energy in the form of electromagnetic radiation.