The cluster contains more than 100,000 stars in an area about 150 light-years across, so they are packed much more tightly than are the stars in our neck of the galactic woods. The nearest stars to the Sun are in the Alpha Centauri system, about 4.36 light-years away.

One recent study suggested that stellar collisions in a cluster like M13 could fuel a runaway situation leading to the development of a black hole.

Most of the M13's stars are very old, more than 12 billion years, and like other clusters of its kind it is considered a window to the ancient universe, which is about 13.7 billion years old. The Milky Way and other galaxies are thought to have built their bulk by consuming globular clusters and small galaxies.

The picture was taken last week by amateur astrophotographer Johannes Tan, with the help of a professional astronomer, at a nightly observing program at the Kitt Peak National Observatory in Arizona. The program is designed to introduce total amateurs to the art and science of astronomy and astrophotography.

• See the center of M13
• See M5, a similar cluster

-- Robert Roy Britt