The Calabash Nebula, also known as the Rotten Egg Nebula or by its technical name OH 231. 84 +4. 22, is a protoplanetary nebula (PPN) 1. 4 light years (13 Pm) long and located some 5,000 light years (47 Em) from Earth in the constellation Puppis. The name "Calabash Nebula" was first proposed in 1989 in an early paper on the expected nebular dynamics, based on the nebula's appearance The Calabash is an almost certain member of the open cluster Messier 46, as it has the same distance, radial velocity, and proper motion.