The Andromeda Galaxy is a barred spiral galaxy about 2.48 million light-years away from Earth, located in the constellation Andromeda. It is officially designated Messier 31 (M31), or NGC.

The Andromeda Galaxy is a spiral galaxy approximately 2.5 million light-years (2.4×1019 km) from Earth in the Andromeda constellation. Also known as Messier 31, M31, or NGC 224, it is often referred to as the Great Andromeda Nebula in older texts. The Andromeda Galaxy is the nearest spiral galaxy to our Milky Way galaxy, but not the nearest.

This ambitious photographic cartography of the Andromeda galaxy represents a new benchmark for precision studies of large spiral galaxies that dominate the universe's population of over 100 billion galaxies. Never before have astronomers been able to see individual stars inside an external spiral galaxy over such a large contiguous area.