Supernova 1987a remnant, combined Hubble Space Telescope optical image and Chandra X-ray telescope image. The bright pink inner ring reveals X-rays emitted as material ejected by the explosion impacts the inner surface of a shell of material ejected before the star exploded as a supernova. This shell of material was revealed soon after the supernova as ultraviolet radiation from the blast ionised gases in it, causing them to emit light. This emission is seen in other parts of the shell (red rings above and below X- ray ring). As the shock wave moves outwards it will cause more gas to emit X-rays, making the ring brighter. The Chandra image was taken on 9th January 2005.