The Hercules star cluster is one of the telescopic gems of the night sky. It is located in the constellation Hercules. Even in relatively small telescopes, the cluster’s appearance in the eyepiece is that of a globe of diamonds on black velvet. The cluster was discovered by Edmond Halley (of comet fame) in 1714, and is also known as M13, as cataloged by Charles Messier in 1764. M13 is a globular cluster, so designated because of its spherical or globe shape, and is composed of about 300,000 stars, 25,100 light-years from Earth. The stars in a globular cluster are of about the same age, having formed together from the same molecular cloud. The photograph shown here illustrates M13 as it may appear to the eye through the eyepiece of a small telescope — click on the image to enlarge. While larger telescopes and sophisticated imaging techniques reveal still greater detail and beauty in the Hercules Globular Cluster, it remains impressive without those enhancements.
Stephens Memorial Observatory 