The Veil Nebula is what remains of a star that exploded thousands of years ago. It is located some 2,500 light years from Earth in the constellation of Cygnus, the Swan. Expanding sheets and filaments of hydrogen gas stretch across roughly 100 light years of interstellar space. In our sky, the Veil is huge — nearly four full-moon widths across.
In this image, special filters were used to isolate light emitted by specific elements in the nebula. Red represents sulphur, green indicates hydrogen, and blue highlights oxygen emission. Click here to see an image of just the hydrogen emission.