Tuesday, July 08, 2003

Why Supernovae Matter

A supernova is a stellar explosion; it occurs when a star of sufficient mass collapses after it has exhausted its fuel; the resulting incredible increase in density drives one final explosion.

When first-generation stars formed, that is, formed from the primordial hydrogen cloud resulting from the Big Bang, of course there could be no planetary system, since there's only hydrogen. Only when that star eventually novas, if it does, will elements heavier than lithium be scattered into the nebula. However, that process only makes elements up to iron; ordinary stellar fusion doesn't have enough energy to create heavier elements. So only supernovas can create those heavy elements, creating a nebula that might later produce planets with elements necessary for life. So, at some point, there must have been a supernova where the Earth's solar system is now, creating the nebula from which the Sun and the planets formed.