It is thought that the nuclear fusion occurring in the sun's core fuses 650 million tons of hydrogen every second, transforming it into helium. The energy generated during nuclear fusion becomes heat, and this heat energy from the core is constantly transmitted to the sun's surface, while keeping the core at high temperature.

The amount of energy the earth receives from the sun is equivalent to as many as 200 million 1-million-kilowatt power plants. Still, since that accounts for only 1/2 billionth of the total energy emitted by the sun, you can easily understand the enormity of its nuclear fusion.

The heat energy transmitted to the sun's surface forms vortices of gas there. The convection of these vortices sometimes results in powerful magnetic fields. Whenever there is a concentration of magnetic fields on the sun's surface, explosive events known as sunspots and solar flares occur.