Globular clusters are hundreds of thousands of stars packed into a tightly jammed ball, each orbiting the cluster center like a bee circling a hive. NGC 6934
is one such globular, a single example of more than 150 that orbit our Milky Way Galaxy. It's 50,000 light years, such a great distance that its magnificence is greatly reduced, making it not much more than a fuzzy blob through most telescopes... unless you happen to have the Hubble Space Telescope at your command. Then this bustling city of stars becomes a dazzling jewel.
This image is false color; what you see as blue is actually taken through a red filter, and what looks red is actually infrared
. Astronomers sometimes do this with two-filter images, to help our eyes separate out the colors.
In this case, it shows that most of the stars in the cluster are probably lower mass than the Sun, still fusing hydrogen into helium in their cores, but a few have aged to the point of becoming red giants, swelling up and cooling off. Such is the fate of our Sun in a few billion years... and studying distant globular clusters like NGC 6394 helps us understand how how our nearest star will someday die. I picked this image because it's a relatively unheard-of but beautiful cluster... and I love the way the stars look like jewels. Get the high-res version here.Image credit: ESA, Hubble, NASA