This ribbon-like cloud is a small section of an expanding supernova remnant created by a shock wave that heats and ionizes surrounding ambient gas. The supernova is cataloged as SN1066. Light from that supernova reached Earth in 1066 AD, and the “guest star” was visible for a couple of years, at times brighter than Venus. The remnant is still expanding and is over 60 light-years across.

Image Credit: NASA / ESA