Cygnus Loop

The Cygnus Loop, also known as the Veil Nebula Complex, is a shockwave from a 20,000 year-old supernova explosion, still expanding into interstellar space. The collision of this fast moving wall of gas with a stationary cloud has heated it causing it to glow in visible as well as high energy radiation, producing the nebula known as the Loop (NGC 6960/95).