Nightscapes & Deep Sky Colors
Astrophotography © Brian A. Morganti
M101 "Pinwheel Galaxy"
75% crop resolution view of M101 below
Messier 101 is a classic type Sc, face-on, spiral galaxy in Ursa Major. It is located 25 million light-years away. Like M33, it is also often referred to as the Pinwheel Galaxy.
Numerous HII emission nebulae and star-forming regions in M101 are visible in this image. Bright pink knots in the spiral arms are gigantic clouds of glowing hydrogen gas ionized by hot young stars in clusters that formed out of the gas. An asymmetry can be seen in the spiral arms of M101 and is believed to be caused by a near collision with another galaxy. The interaction caused density waves in the spiral arms to be amplified, compressing the hydrogen gas, leading to bursts of star formation.
M101 is twice the size of the Milky Way at 170,000 light-years in diameter, with a mass of 100 billion suns. At least 5 other galaxies can be found in the wide field image at the top of this page. The largest being Spiral Galaxy NGC5474 in the lower right-hand corner, with the smallest being PGC49919 barely visible as a faint edge on Spiral Galaxy to the left of the bright blue star above M101.
Astrophotography - Nightscapes & Deep Sky Colors