The Crab Nebula
The Crab Nebula (Messier 1) is a supernova remnant in the constellation Taurus 6,500 light years from Earth. The supernova was observed by Chinese astronomers in the year 1054 AD and called it a “guest star” that was visible in the daytime sky for about a month. At the heart of the nebula is a Neutron Star which is the remains of the star that exploded in 1054 AD. The Crab Nebula does not have the normal bubble shape of a Blast wave driven supernova remnant, but rather has an elliptical shape with filliament structures throughout. Rather than being a blast wave driven supernovae it is a Pulsar Wind Nebula. The Neutron Star at the centre of the nebula is rotating at about 30 times a second and emitting beams of radiation driven by the rapidly rotating magnetic fields of the star, which results in the star pulsing at 30 times a second and so it is called a Pulsar. The huge amount of energy from this Pulsar is what drives the nebula. It is one of the few objects in the night sky that can be observed as changing over time.