Stars are one of the beautiful objects in space. When we think of stars, we get an image of a twinkling star shaped object. But stars are not in star shape! Every star is a hot ball of glowing plasma. They shine because of nuclear fusion reaction that takes place at the centre.

What is nuclear fusion reaction?

Nuclear fusion reaction is simply a process in which smaller elements fuse together to form higher elements. Like two hydrogen atoms fuse together to form Helium. This releases an enormous amount of energy in the form of Gamma rays.

The Sunlight

We have a star in our solar system that acts as a source of energy. All the planets revolve around the Sun. Like any other star, our sun also performs nuclear fusion reaction. That's how it produces light!!

Nuclear fusion reaction produces gamma rays. But why do we get visible light?

It's because the light released from nuclear fusion reaction gets hit by an atom and then bounces back and gets hit by another atom. There are millions of atoms inside the Sun. So the gamma ray released undergoes collisions for about 100,000 years before it reaches the surface of the Sun. Once it reaches the surface of the Sun, the light has already lost most of it's energy because of collisions. So the light now falls under visible spectrum. Hence we see visible light.

The light then escapes the surface of the Sun and travels in straight line forever if not interrupted!

It takes about 8 minutes for sunlight to reach to the Earth.

The light we experience is produced around 100,000 years ago!!

So the next time you feel sunlight, think about how the light has undergone so much to get this far!!