Something similar to this came up in a lecture but it wasn't explained very well. From wikipedia it seems that our sun is made up of 74.9% Hydrogen and 23.8% Helium. The final 1.3% is made up of heavier elements such as oxygen, carbon, neon, and iron. If the the entire solar system condensed out of the same cloud of matter, how come the planets are composed of such different materials to the sun? Where do the other elements come from? I heard that heavier elements were thought to be made in supernovae, but then also heard that that was just a theory made to hide the fact that no one really knows. Does this mean that there would have been a previous star in this general area in space we occupy that went supernova, then our current solar system was created out of the remains?