M15 (in the constellation of Pegasus) is an easy target for backyard astronomers. On a clear night, it’s visible as fuzzy spot with a decent pair of binoculars. A 150-mm or larger telescope will reveal some individual stars in the cluster. Here’s what it looks like using Hubble.
The cluster is estimated to be one of the oldest known, about 12 billion years old. It contains over 100 variable stars, eight known pulsars, and a double neutron star. Its central region has undergone core collapse and may contain a black hole.
Image Credit: NASA