M15

Object Type: Planetary Nebula
Scope: APO 80mm; Exposure 95 minutes.

Messier 15 (NGC 7078) is a globular cluster in Pegasus, discovered by Jean-Dominique Maraldi in 1746. At roughly 13.2 billion years old it is one of the oldest known globulars, lying about 33,600 light-years away. It is among the most densely packed clusters in the Milky Way: its core has undergone 'core collapse,' concentrating an enormous number of stars, possibly around a central black hole. M15 is also unusual for containing a planetary nebula (Pease 1), over 100 variable stars, and at least eight pulsars.