M13 (Great Globular Cluster in Hercules)

Constellation: Hercules

Distance: 25,100 Light Years

Globular clusters are ancient structures with a minimum age of 11 billion years, probably formed at the same time as their parent galaxy. The Great Globular Cluster in Hercules is arguably the finest globular cluster visible from the northern hemisphere, and can be glimpsed with the unaided eye from a dark sky site. It contains about 500,000 stars in a span of only 150 light years. (Information from A Year in the Life of the Universe by Robert Gendler, and The 100 Best Astrophotography Targets by Ruben Kier).

The small galaxy at the northeast edge of the cluster (upper right in this image) is IC 4617.