The Crab Nebula (Messier 1) is the remnant of a supernova that exploded in the year 1054 AD. This mysterious "new star," as early sky watchers called it, was observed around the world and most notably recorded by Chinese astronomers. The supernova was triggered when the progenitor star abruptly collapsed onto its iron core, and rebounded to expel most of its layers of gas into a blast wave. This wave is seen as an optical and infrared set of filaments that continues to impact surrounding material. This material was expelled from the dying red giant progenitor star 20,000 years prior to the supernova. The ultra-dense remnant core, called a neutron star, is crushed to the size of a city. Spinning furiously, the neutron star sends out twin beams of radiation, like a lighthouse. A lot of this energy comes from the neutron star’s intense magnetic fields.
The initial radio image (from the Very Large Array) shows the cool gas and dust blown out by the supernova winds. The infrared (Spitzer) image shows synchrotron radiation, an unusual form of light produced by electrons trapped in magnetic fields. The infrared image also shows hot gas.The visible-light image (Hubble) shows the detailed filamentary structure of the blast wave as it impacts the surrounding material. The ultraviolet image (XMM-Newton) shows hot, ionized gas. Finally, the X-ray emission (Chandra) from high-energy particles ejected from the pulsar shows the expanding nebula. The bipolar structure represents a powerful jet of material funneled along the neutron star's spin axis.