How come the sun is so hot?
Our Sun is a star and releases an abundance of energy in the form of electromagnetic radiation, including visible light. This energy comes from nuclear fusion, a process that takes place within the Sun. The main process responsible for the high temperatures of our sun is the fusion of hydrogen into helium. In a sense, the hydrogen is the fuel of our Sun and the helium the ashes. The surface of the Sun – at about 5500 degrees Celsius – is indeed much colder than the Sun’s core but still very hot when you compare it to temperatures on Earth.
