M1, the first object in Charles Messier's famous catalog, is the Crab Nebula. It is the remains of a supernova, a star that exploded in 1054 AD and left behind this expanding cloud of gas. The supernova was so bright, it was visible during the daytime. It is located in the constellation of Taurus about 6,300 light years away. Its apparent size is 6 x 4 arc minutes and its visual brightness is magnitude 9.4. Astrophotos taken 30 years apart show the expansion of the nebula in real time. Today, the cloud of debris left behind by the supernova has expanded to about 10 light years in diameter. The nebula was first discovered by John Bevis in 1731, and independently discovered by Messier in 1758.