supernova: When a very large star is at the end of its life cycle and uses up all its fuel it explodes. The explosion is called a supernova. The explosion is very violent. The supernova may shine for days or weeks. A supernova shines with the brightness of 100 billion other stars put together! When a star becomes a supernova, it blasts away its outer layers. The material that the supernova throws into space may form a nebula.
