You should also read about how stars form and evolve over time: * http://en.wikipedia.org/wiki/Stellar_evolution http://en.wikipedia.org/wiki/Stellar_evolution

You should also read about how stars form and evolve over time: * http://en.wikipedia.org/wiki/Stellar_evolution http://en.wikipedia.org/wiki/Stellar_evolution * http://en.wikipedia.org/wiki/Main_sequence http://en.wikipedia.org/wiki/Main_sequence