Astronomy Picture of the Day . ... Aristarchus lived on the Greek island of Samos, a small island in the center of the above picture that can be identified with a good map. ... Our Milky Way galaxy appears to be surrounded by a halo of gamma rays. ... Blue Stagglers in Globular Clusters . ... Irregular Moons Discovered Around Uranus . ... This Hubble Space Telescope image covers a small region near the center of a globular cluster known as M4. M31: The Andromeda Galaxy . ...