The Triangulum Galaxy is a spiral galaxy 2.73 million light-years (ly) from Earth in the constellationTriangulum. It is catalogued as Messier 33 or NGC 598. The Triangulum Galaxy is the third-largest member of the Local Group of galaxies, behind the Andromeda Galaxy and the Milky Way. It is one of the most distant permanent objects that can be viewed with the naked eye.