Messier 15 (NGC 7078) is a globular cluster containing more than 100.000 stars as well as possibly a central black hole, it is located in the constellation Pegasus. The distance is about 33.000 light years, the cluster has a diameter of about 175 light years. It was discovered in 1746 and included in Charles Messier’s catalogue in 1764.
The age of this cluster is estimated at about 12 billions years.
It is one of the oldest known globular clusters.
M15 also contains Pease 1, the first planetary nebula discovered (in 1928) within a globular cluster. It is not visible in this image though.
At magnitue 6.2 it may reach naked eye visibility under very good (dark) sky conditions.