The Triangulum GalaxyThe Triangulum Galaxy is a spiral galaxy 2.73 million light years from Earth in the constellation Triangulum. It is catalogued as Messier 33 or NGC (New General Catalogue) 598. With the D25 diameter of 18.74 kilo parsecs (61,100 light years), the Triangulum Galaxy is the third-largest member of the local group of galaxies, behind the Andromeda Galaxy and the Milky Way.