Question: How do stars ignite?

Nick Wright answered on 11 Mar 2014:

Stars burn hydrogen in their centre, at temperatures of millions of degrees Celsius. The heat from this travels outwards through the star to their surface causing them to glow – while it looks like stars are ‘on fire’ on their surface they aren’t burning anything on the surface in a way we know. In their centers stars only start burning hydrogen when they get really really hot, and this can only happen when there’s lots of material in the star pushing down on the middle due to gravity. So for the stars to ignite and start burning hydrogen they need to build up lots of material. They do this by forming out of giant gas clouds in space, attracting lots of gas through gravity until they have enough to ignite their burning.