High Energy Andromeda . ... Credit Copyright: NASA , JPL-Caltech, GSFC, NuSTAR , GALEX , Explanation: A mere 2.5 million light-years away, the Andromeda Galaxy, also known as M31, really is just next door as large galaxies go. ... In fact, larger Andromeda and our own Milky Way are the most massive members of the local galaxy group. ... The background image of Andromeda was taken by NASA's Galaxy Evolution Explorer in energetic ultraviolet light. ... A service of: LHEA at NASA / GSFC . ...