The Andromeda Galaxy (M31)

The Andromeda Galaxy is our nearest large galactic neighbour — a vast spiral system over two million light-years away, and the most distant object visible to the naked eye.

Messier 31 is a spiral galaxy roughly 2.537 million light-years from Earth in the constellation Andromeda. It is larger than the Milky Way — spanning some 220,000 light-years across — and is accompanied by several satellite galaxies, most notably M32 and M110, which are often captured in the same field.

Andromeda and the Milky Way are on a collision course, expected to merge in approximately 4.5 billion years. For now, it drifts toward us at around 110 kilometres per second — its ancient light arriving here after more than two million years of travel.

The sheer angular size of Andromeda — it spans roughly six times the diameter of the full Moon on the sky — means that capturing it in full requires either a very short focal length or a mosaic. The outer halo and the faint tidal streams are some of the most challenging and rewarding details to pull out.