It is said that supernovas can only come from red giants. If that is so then how come the supernova that occurred approximately 1000 years ago was seen to have happened from a blank piece of sky in the constellation Taurus. It was the "quest star" according to the Chinese. Wouldnt a red giant have been visible or any star for that matter but especially a red giant in that part of the sky BEFORE the supernova. I mean after all a red giant at that close proximity (the crab nebula is not that far away in cosmic terms) would have been seen would it not ? This question been on my mind some time. Please help to answer.