Stars Young and Old
26.03.2009

Galactic or open star clusters are relatively young. These swarms of stars are born near the plane of the Milky Way, but their numbers steadily dwindle as cluster members are strewn through the Galaxy by gravitational interactions.

Stars Young and Old
4.08.2005

Galactic or open star clusters are relatively young swarms of bright stars born together near the plane of our Milky Way Galaxy. Separated by about a degree on the sky, two nice examples...

Open Cluster M50
28.01.1997

Many stars form in clusters. Two types of star clusters are visible in our Milky Way Galaxy: open clusters and globular clusters. Open clusters like M50, shown above, typically contain hundreds of stars, many of which are bright, young, and blue.

The Cartwheel Galaxy
12.06.2001

By chance, a collision of two galaxies has created a surprisingly recognizable shape on a cosmic scale. The Cartwheel Galaxy is part of a group of galaxies about 500 million light years away in the constellation Sculptor. Two smaller galaxies in the group are visible on the left of the above photograph.

In the Center of the Trapezium
10.07.2005

Start with the constellation of Orion. Near Orion's belt is a fuzzy area known as the Great Nebula of Orion or M42. In this nebula is a bright star cluster known as the Trapezium, shown above. New stellar systems are forming there in gigantic globs of gas and dust known as Proplyds.

NGC 869 and NGC 884: A Double Open Cluster
11.10.2005

Most star clusters are singularly impressive. Open clusters NGC 869 and NGC 884, however, are doubly impressive. Also known as "h and chi Persei", this unusual double cluster, shown above, is bright enough to be seen from a dark location without even binoculars.

The Pleiades Star Cluster
6.05.2001

It is the most famous star cluster on the sky. The Pleiades can be seen without binoculars from even the depths of a light-polluted city. Also known as the Seven Sisters and M45, the Pleiades is one of the brightest and closest open clusters.

NGC 6791: An Old, Large Open Cluster
12.01.2000

NGC 6791 is one of the oldest and largest open clusters of stars known. But how did it get so dirty? Open star clusters usually contain a few hundred stars each less than a billion years old.

NGC 4755: A Jewel Box of Stars
17.08.2010

The great variety of star colors in this open cluster underlies its name: The Jewel Box. One of the bright central stars is a red supergiant, in contrast to the many blue stars that surround it. The cluster, also known as Kappa Crucis contains just over 100 stars, and is about 10 million years old.

In the Center of 30 Doradus
4.10.1997

In the center of 30 Doradus lies a huge cluster of the largest, hottest, most massive stars known. The center of this cluster, known as R136, is boxed in the upper right portion of the above picture.