Secrets of the Crab: The Crab Nebula [left] is perhaps the most conspicuous and well-known gaseous remnant of a supernova in the Milky Way galaxy. Chinese astronomers first observed it on 4 July 1054. Astronomers hope the Laser Interferometer Gravitational Wave Observatory [right] will be able to detect gravitational waves created by cosmic events like supernova explosions and galactic collisions.