Sally and Curt King/Adam Block/NOAO/AURA/NSF

Star clusters are not the most widely celebrated astronomical objects, but they can be photographic jewels. This picture is of M5, a globular cluster that resides in the Milky Way Galaxy and is visible from the Northern Hemisphere. The stars are bound together by mutual gravity, behaving a bit like a miniature galaxy within our galaxy.

The picture was taken last month by an amateur, 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.

Adam Block, who helps guide novices in the program, says this about clusters like M5: "These balls of stars (upwards of a million members) orbit our galaxy on the order of tens of thousands of light-years distant. This particular cluster is approximately 26,000 light-years away and is estimated to be 13 billion years old."

That's nearly as old as the universe itself. Astronomers think the Milky Way Galaxy has built its bulk over the eons in part by swallowing globular clusters and other small galaxies. [About the Kitt Peak Program]

-- Robert Roy Britt