Spiral galaxy M Hubble Space Telescope image M is also known as the Pinwheel Galaxy It lies around million light years from Earth in the constellation Ursa Major The disc of the galaxy is some light years across nearly twice as wide as our own Milky Way The spiral arms appear blue as they contain hot young stars The central nucleus is yellow as the stars there are older and much of the light is obscured by dust Released in this is the most detailed image of a galaxy ever taken by the HST It is composed of separate HST exposures taken between and which were superimposed on groundbased images The full Mb image is available on request