This composite image of X-rays from Chandra and optical data from Hubble shows new details of the aftermath of a massive star that exploded and was visible from Earth over 1,000 years ago. The Chandra image shows an outer blast wave produced by the supernova (blue) and an inner ring of cooler (red-orange) material. By examining the spectra of the X-rays, astronomers have new information about the geometry of the remnant, which, in turns, has implications for the nature of this explosion.