The M101 Pinwheel Galaxy is a magnificent face-on spiral galaxy located about 21 million light-years away in the constellation Ursa Major. Known for its enormous size—nearly twice the diameter of the Milky Way—M101 displays a classic “pinwheel” structure with long, gracefully sweeping spiral arms radiating from a relatively small, bright core.

These spiral arms are rich in star-forming regions, glowing pink from vast clouds of ionized hydrogen and dotted with brilliant blue clusters of young, hot stars. Dark lanes of cosmic dust thread through the arms, adding depth and contrast to the galaxy’s intricate design. The uneven appearance of the arms is thought to be the result of gravitational interactions with several nearby companion galaxies.

For astronomers and astrophotographers, M101 is a showcase of spiral galaxy evolution and active star birth. While its light is spread over a large area—making it somewhat challenging to observe visually—long-exposure images reveal one of the most detailed and beautiful spiral patterns in the night sky, earning M101 its evocative name, the Pinwheel Galaxy.