03 January 2003
Vol 299, Issue 5603

About The Cover

Cover image expansion

COVER Messier 13, visible in the Hercules constellation, is a globular cluster in the halo of the Milky Way galaxy about 23,000 light-years distant. Globular clusters orbit galaxies and contain hundreds of thousands of stars bound together by mutual gravitational attraction. They are thought to be among the oldest stellar systems in the universe. 59 [Image: J. C. Cuillandre, Canada-France-Hawaii Telescope; see]