The nearest large galaxy, about 2.5 million light-years away, and on a collision course with the Milky Way.
The Andromeda Galaxy is the nearest large spiral galaxy to the Milky Way, about 2.5 million light-years away. It is the most distant object you can see with the naked eye, as a faint smudge in the constellation Andromeda.
The light you see from Andromeda left the galaxy about 2.5 million years ago, long before modern humans existed.
A future collision
Andromeda and the Milky Way are moving towards each other. For a long time astronomers expected them to collide in about 4 to 5 billion years. Newer measurements published in 2025 suggest that the chance of a merger within the next 10 billion years is only about 50%. Even if the galaxies collide, stars are so far apart that they will almost never hit each other directly.
The image above is part of a giant mosaic that was, at its release in 2015, the largest image ever assembled from Hubble data. It resolves more than 100 million individual stars in the disc of the Andromeda Galaxy.