M1, the Crab Nebula, is a supernova remnant from a star that exploded in July or August of 1054 AD and was witnessed and described by Chinese astronomers as being six times brighter than Venus. The supernova, located in the constellation of Taurus about 7,000 light years away from the Earth, shone with the light of 400 million suns and was visible in the daytime for almost a month. (It remained visible in the evening sky for more than a year.) More than 900 years later we see the remains of the exploded star as a cloud of gaseous debris, illuminated by the remnants of the original star's core, which is now a rapidly spinning neutron star called a pulsar. The colors in the nebula come from two different sources. The red filaments come from typical hydrogen emission such as is found in emission nebula like M8. The diffuse blue background has a continuous spectrum composed of synchrotron radiation which is emitted by high energy electrons in a powerful magnetic field.