Flexi Says: The Sun is a medium star which will become a white dwarf at the end of its life cycle. A more massive star ends its life in a more dramatic way. When there is nothing left to fuse, the star’s iron core explodes violently. This is called a supernova explosion. The incredible energy released fuses heavy atoms together. The elements heavier than iron form in supernova explosions, including gold, silver and uranium. A supernova can shine as brightly as an entire galaxy, but only for a short time.