4000 light-years

Strikingly beautiful, even by nebula standards, the Cocoon Nebula glows pink in the light of hydrogen gas ionised by the large star at centre. This star formed about 100,000 years ago, and its ultraviolet light has carved this nebula out of a vast, dark cloud of gas and dust. We are looking at the nebula through a hole in the side of this cloud.

Credit: Image made in visible light by Jean-Charles Cuillandre for the Canada-France-Hawaii Telescope Corporation.