Discovered by William Herschel on September 5, 1784 the nebula lies about 1,500 light-years away, and the filaments of gas and dust have been heated by a shock wave from a supernova that is still spreading outward left over from a massive stellar explosion that occurred 5,000 to 8,000 years ago. The Cygnus loop exceeds three times the size of the full moon and is tucked next to one of the “swan’s wings” in the constellation of Cygnus.
The original supernova would have been bright enough
to be seen clearly from Earth with the naked eye
J2000 RA 20h 51.1m | Dec +30° 41′