Object Analysis

The Pinwheel Galaxy (Messier 101) is a face-on spiral galaxy distanced 21 million light-years away in the constellation Ursa Major. It was discovered by Pierre Méchain in 1781 and was communicated to Charles Messier, who verified its position for inclusion in the Messier Catalogue.

M101 is a large galaxy, with a diameter of 170,000 light-years, making it nearly twice the size of the Milky Way. It contains around a trillion stars. It has a high population of H II regions, many of which are so large and bright that they have their own NGC numbers.

The galaxy is asymmetrical due to tidal forces from interactions with its companion galaxies. These interactions have triggered intense star formation in its spiral arms and distorted its shape, giving it a "lopsided" appearance.