Crab Nebula

Cloud of gas 6,000 light years from Earth, in the constellation Taurus. It is the remains of a star that, according to Chinese records, exploded as a supernova observed as a brilliant point of light on 4 July 1054. At its centre is a pulsar that flashes 30 times a second. It was named by Lord Rosse after its crablike shape.

It is a powerful radio and X-ray source. Optically it appears as a diffuse elliptical area on which is superimposed an intricate network of bright filaments. Observations show that it is increasing in size. Its present dimensions are of the order of 10 light years. The light is highly polarized, suggesting the presence of strong magnetic fields. This suggestion is strengthened by the fact that the diffuse portion is emitting radiation throughout the whole electromagnetic spectrum from radio to gamma waves, the energy coming from the pulsar near the centre.