Messier 101 The Pinwheel galaxy

Fred Calvert, Cold Spring Observatory

Messier 101, also known as the Pinwheel galaxy, is a face-on spiral galaxy 21 million light-years away in the constellation Ursa Major and was first discovered by Pierre Méchain on March 27, 1781. The Pinwheel is a large grand design spiral galaxy with a diameter of 170,000 light-years, seventy percent larger than our Milky Way Galaxy. A grand design spiral galaxy is a type of spiral galaxy with prominent and well defined spiral arms that extend clearly around the galaxy through many radians and can be observed over a large fraction of the galaxy’s radius. Approximately 10 percent of spiral galaxies are classified as the grand design type. About 3000 extremely bright H II (red regions) can be seen in M101. H II regions usually accompany enormous clouds of high density molecular hydrogen gas contracting under their own gravitational force, where stars form. They are ionized (causing them to glow) by large numbers of extremely bright and hot young stars.

This image was taken remotely from Cold Spring Observatory using a Planewave 12.5”Corrected Dall-Kirkham Astrograph Telescope and SBIG 6303E CCD Camera located in Nerpio, Spain using the i-Telescope network.

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