Messier 101

Messier 101 (M101), also known as the Pinwheel Galaxy, is a large spiral galaxy located in the constellation Ursa Major, about 21 million light-years from Earth. Discovered in 1781 by Pierre Méchain and later included in the catalog of Charles Messier, M101 is one of the most impressive face-on spiral galaxies visible from Earth.

The galaxy spans roughly 170,000 light-years, making it even larger than the Milky Way Galaxy. It contains hundreds of billions of stars and many bright regions of active star formation within its well-defined spiral arms. Because of its size, structure, and ongoing stellar birth, M101 is an important target for astronomers studying how galaxies evolve.

Despite its enormous size, Messier 101 appears faint in small telescopes, but under dark skies it can be observed as a soft, diffuse patch of light.