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 own Milky Way galaxy, but not the closest galaxy overall. (from Wikipedia).