The Triangulum Galaxy (Messier 33, also cataloged as NGC 598) is a face-on spiral galaxy located about 2.7 million light years away in the constellation Triangulum. Spanning roughly 60,000 light years across, it is about half the diameter of our own Milky Way and holds an estimated 40 billion stars. It is the third-largest member of the Local Group, after the Andromeda Galaxy and the Milky Way, and is likely a gravitationally bound satellite of Andromeda. Its loosely wound spiral arms are dotted with brilliant pink and blue star-forming regions, including NGC 604, one of the largest known stellar nurseries, which is more than 40 times the size of the Orion Nebula and visible in this image as the bright knot at the upper right of the galaxy’s disk. Under very dark skies, M33 is just barely visible to the naked eye, making it one of the most distant objects the unaided human eye can see, though its low surface brightness makes it a notoriously challenging target for casual observers.