The Veil Nebula is a cloud of heated and ionized gas and dust in the constellation Cygnus. It constitutes the visible portions of the Cygnus Loop, a large but relatively faint supernova remnant. The source supernova exploded some 5,000 to 8,000 years ago, and the remnants have since expanded to cover an area roughly 3 degrees in diameter. The distance to the nebula is not precisely known, but recent evidence from the Far Ultraviolet Spectroscopic Explorer (FUSE) supports a distance of about 1,470 light-years.