Question: How does a star form ?

Chris Conselice answered on 11 Mar 2016:

Stars form from collapsing from gas.

Imagine a big gas cloud. Overtime gravity will collapse it to a very dense gas cloud. When this happens the gas will become so dense that the atoms in it will smash together like in a nuclear explosion. This produces light – like we see in the Sun. All the light from stars comes from these nuclear explosions happening due to the smashing together of atoms in very dense gas.