M101 – The Pinwheel Galaxy M101 is one of the most impressive face-on spiral galaxies in the northern sky. It was discovered by
Pierre Méchain in 1781, and was verified by Charles Messier, who then included it in his catalog.M101 is located in the constellation Ursa Major at a distance of 21 million lights years from Earth. It has a diameter of approximately 170,000 light years and is estimated to contain a trillion stars. By comparison, the Milky Way is smaller at 100,000 – 120,000 light years in diameter and 100-400 billion stars.M101 is a so-called grand design spiral galaxy; these are spirals with well-defined spiral arms that extend outward from the body. It contains a number of star-forming regions (HII regions), which exhibit as pinkish areas in most images. Many of these are thought to have arisen due to gravitational interaction with a nearby galaxy.M101 anchors the M101 Group of galaxies, with six additional members: NGC5204, NGC5474, NGC5477, NGC5585, UGC8837, and UGC9405. This group, in turn, is part of the Virgo Supercluster.
Comments