Discovered 1731 by British amateur astronomer John Bevis.
The Crab Nebula, created by the explosion of a massive star, is located in the constellation Taurus, and is possibly the most famous supernova remnant in the sky. It was observed, and documented, by Chinese astronomers on July 4, 1054. The "new star" was about four times brighter than Venus. It was so bright that it could be seen in daylight for 23 days and 653 days in the night sky.
Charles Messier independently found the nebula on August 28, 1758 when he was looking for comet Halley on its first predicted return. He first thought it was a comet but soon recognized that it had no apparent proper motion. It was the discovery of this object which caused Charles Messier to begin the compilation of his famous catalog.
The nebula consists of material ejected by the supernova explosion. The nebula has expanded over a volume of space approximately 10 light years in diameter. It is still expanding at a velocity of about 1,800 km/sec. It emits light consisting of two major contributions. First, a reddish component which forms a chaotic web of bright filaments consisting mainly of excited hydrogen. Second, a blueish diffuse background consisting of highly polarized synchrotron radiation emitted by high-energy electrons in a strong magnetic field.
On November 9, 1968, a pulsating radio source, the Crab Pulsar, was discovered in M1 by astronomers using the Arecibo Observatory's 300-meter radio telescope in Puerto Rico. It has now been established that this pulsar is a rapidly rotating neutron star. It rotates about 30 times per second.
The Crab Nebula is approximately 6,300 to 6,500 light-years distant.