M46 & M47

Object Type: Planetary Nebula
Scope: APO 80mm; Exposure 35 minutes.

Messier 46 (NGC 2437) and Messier 47 (NGC 2422) are two open star clusters about a degree apart in Puppis, fitting together in a binocular field. M46, discovered by Messier in 1771, is the richer of the two - about 500 stars, some 300 million years old, and roughly 5,500 light-years away. The small planetary nebula NGC 2438 appears projected on M46's northern edge but is almost certainly a foreground object, not a true cluster member, since it does not share the cluster's motion.