A Star is Born

New stars froming in M16

The cloud slowly shrinks and collapses towards its centre because of gravity.

Right in the middle, it can get very hot and dense. When this happens, nuclear fusion can start and the star is born. This is called stellar ignition.

The sudden burst of light made by the new star blows away most of the rest of the cloud of gas, although some may be left which might form planets much later.

You can see what is happening in a bit more detail in this simulation.

At this point the star becomes relatively stable, with the outward pressure from nuclear reactions balancing the inward pull of gravity.

A typical star like the Sun will live for around 10 billion years, until it eventually runs out of fuel. All stars go through a life cycle in the same way that we do - they just live longer.

Let us now look at the ways in which stars can end their days.