The Pinwheel Galaxy is a face-on spiral galaxy located 21 million light-years away in the constellation Ursa Major. It was first discovered by Pierre Méchain on March 27, 1781, and communicated to Charles Messier, who verified its position for inclusion in the Messier Catalogue as one of its final entries. This image, released on February 28, 2006, is composed of 51 individual exposures, as well as some extra ground-based photos. At the time of its release, it was the largest and most detailed image of a galaxy by the Hubble Space Telescope.Photograph: European Space Agency and NASA