The visible remnant of a supernova that exploded roughly 8,000 years ago in Cygnus, about 2,400 light-years away. The blast wave from that explosion is still expanding outward at over 600,000 km/h, ploughing into the surrounding interstellar medium and heating it to millions of degrees. What we see as the Veil is the thin shock front where that interaction produces visible light — a cosmic shockwave frozen in time.

The nebula spans nearly 3 degrees of sky — six times the diameter of the full moon — and is typically divided into the Western Veil (NGC 6960, also known as the Witch's Broom), the Eastern Veil (NGC 6992/6995), and the fainter Pickering's Triangle (NGC 6979) in between. The lacework of filaments visible in narrowband imaging traces the exact boundary where the expanding blast meets denser pockets of gas.