False-colour optical (6090 Angstroms) image of the Crab Nebula (M1, NGC 1952), a supernova remnant 6300 light years away in the constellation of Taurus. The supernova explosion was recorded in 1054 A.D. by Chinese astronomers. The Crab Nebula is the brightest supernova remnant and has a diameter of about six light years. Near the centre of the nebula lies a rapidly spinning neutron star, the Crab Pulsar (the lower of the two central stars), which represents the core of the exploded star. The colour code runs from red for the brightest regions declining to yellow, green, blue and grey.