The Crab nebula is a supernova remnant, which resulted from a supernova explosion that occurred in 1054 A.D
Asked by Lawrence Hilton
A double supernova is a term reserved for two supernovae, which have been detected within short periods of time. Usually we expect a supernova per galaxy roughly every 25 to 100 years, but occasionally they are a little closer together. Of course it is entirely possible that two supernovae could happen simultaneously, but we would have to be positioned equidistant from each one in order to see them light up together.
Answered by Josh Barker from the National Space Centre
Keep up to date with the latest reviews in All About Space – available every month for just £4.99. Alternatively you can subscribe here for a fraction of the price!