Messier 33, the Triangulum Galaxy, is a face-on spiral galaxy in the constellation Triangulum and the third-largest member of the Local Group after the Milky Way and Andromeda.
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Messier 33, the Triangulum Galaxy, is a face-on spiral galaxy in the constellation Triangulum and the third-largest member of the Local Group after the Milky Way and Andromeda. It lies approximately 2.7 million light-years away, with a true diameter of roughly 60,000 light-years. Unlike the more dramatic M31, M33 has a comparatively low surface brightness, making it more challenging to image well from light-polluted skies despite its relatively large apparent size. Its loosely wound spiral arms host numerous star-forming HII regions, most notably NGC 604, one of the largest known star-forming regions in the Local Group. M33 rewards long, dark-sky exposures that bring out its faint spiral structure and pink-tinged nebular knots.
