Veil Nebula supernova remnant, mosaic of six images taken by the NASA/ESA Hubble Space Telescope. This is a section of the expanding remains of a massive star that exploded about 8,000 years ago, known as the Veil Nebula. The entire nebula is 110 light-years across and is about 2,100 light-years away from Earth in the constellation Cygnus. The fast-moving blast wave from the explosion is plowing into a wall of cool, denser interstellar gas, emitting light. The nebula lies along the edge of a large bubble of low-density gas that was blown into space by the dying star prior to its self-detonation. In this image, red corresponds to the glow of hydrogen, green from sulphur, and blue from oxygen. The red glow is from cooler gas that was excited by the shock collision at an earlier time and has subsequently diffused into a more chaotic structure. A few thin, crisp-looking, red filaments arise after gas is swept into the shock wave at speeds of 1.5 million kilometres an hour.