What is the designation of the Andromeda galaxy?

The Andromeda galaxy is designated as M31 in the Messier catalog, which is a collection of astronomical objects compiled by the French astronomer Charles Messier in the 18th century. M31, being the closest spiral galaxy to the Milky Way, has been an important object of study, revealing insights into galaxy formation and evolution. Its designation comes from the fact that it was one of the first objects noted in Messier's catalog and holds significant importance due to its proximity and brightness, allowing for detailed observation.

Other designations provided, such as M32, refer to a dwarf elliptical galaxy that orbits the Andromeda galaxy, while M101 is known as the Pinwheel Galaxy, a separate spiral galaxy entirely. NGC 1234, on the other hand, is another object cataloged in the New General Catalogue, but it does not refer to the Andromeda galaxy. Thus, the clear and widely recognized designation for the Andromeda galaxy remains M31.