M101, widely recognized as the Pinwheel Galaxy, is a face-on spiral galaxy located approximately 21 million light-years away in the constellation Ursa Major. Earning its name from its distinctly symmetrical and well-defined spiral arms, it presents an almost perfect pinwheel shape, evoking the charm of a celestial firework.

Boasting a diameter of about 170,000 light-years, M101 is significantly larger than our Milky Way. Its sprawling arms are filled with billions of stars, vast regions of star-forming nebulae, and clusters that dot its structure, bearing testimony to the dynamic processes at play within.

One of M101's defining features is its high population of H II regions – areas of ionized hydrogen gas – which are notably large and numerous. These regions are indicative of active star formation, painting a picture of a galaxy teeming with stellar birth.