M55, NGC 6809

M55 is a globular cluster in the constellation Sagittarius. Quite large on the sky (about two thirds of the Moon's diameter), but with a very loose, almost non-globular, appearance, M55 is about 18000 light-years away and about 100 light-years across. This composite was created from images taken in June 1996 at the Burrell Schmidt telescope of Case Western Reserve University's Warner and Swasey Observatory, during the Research Experiences for Undergraduates (REU) program operated at the Kitt Peak National Observatory and supported by the National Science Foundation.