M13 • Hercules Globular Cluster
Credit: Harvard-Smithsonian CfA
Observers: Brian McLeod, CfA
Globular star clusters are some of the oldest objects in our galaxy. These clumps of hundreds of thousands of ancient stars - up to 10 billion years old - are tightly held together by gravity. Similar clusters are found throughout the galactic halo surrounding the disk of the Milky Way.