APOD
Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
Globular Cluster M22 from CFHT
Explanation: The globular cluster M22 , pictured above , contains over 100,000 stars. These stars formed together and are gravitationally bound. Stars orbit the center of the cluster, and the cluster orbits the center of our Galaxy . So far, about 140 globular clusters are known to exist in a roughly spherical halo around the Galactic center . Globular clusters do not appear spherically distributed as viewed from the Earth, and this fact was a key point in the determination that our Sun is not at the center of our Galaxy . Globular clusters are very old . There is a straightforward method of determining their age , and this nearly matches the 13.7 billion-year age of our entire universe .
| Date | June 27, 2005 |
|---|---|
| Credit | Credit & Copyright: Jean-Charles Cuillandre (CFHT), Hawaiian Starlight , CFHT |
| Authors & editors: | Robert Nemiroff (MTU) & Jerry Bonnell (UMCP) |
| A service of: |
ASD at NASA / GSFC, NASA Science Activation & Michigan Tech. U. |



