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.