M101 lies 21 million light-years distant from Earth in the constellation Ursa Major. This giant spiral disk of stars, dust and gas is 170,000 light-years across, almost twice the diameter of our Milky Way galaxy. Also know as the Pinwheel Galaxy, M101 is estimated to contain at least one trillion stars. This galaxy portrait is actually composed of 51 individual exposures taken with Hubble's Advanced Camera for Surveys and the Wide Field and Planetary Camera 2 spanning March 1994, September 1994, June 1999, November 2002, and January 2003. It was first discovered by Pierre Méchain on March 27, 1781, and Charles Messier verified its position for inclusion as one of the final entries in the Messier Catalogue. A portion of every Posternauts purchase supports young minds through the scholarship fund of the U.S. Space & Rocket Center® Foundation. Learn More Object Name: M101 (NGC 5457, Pinwheel Galaxy) Release Date: Feb 28, 2006 Image Credits: Credit for Hubble Image: NASA, ESA, K. Kuntz (JHU), F. Bresolin (University of Hawaii), J. Trauger (Jet Propulsion Lab), J. Mould (NOAO), Y.-H. Chu (University of Illinois, Urbana), and STScI; Credit for CFHT Image: Canada-France-Hawaii Telescope/ J.-C. Cuillandre/Coelum; Credit for NOAO Image: G. Jacoby, B. Bohannan, M. Hanna/ NOAO/AURA/NSF
