Andromeda

The Andromeda Galaxy, 31st object in the Messier catalog, is the most distant object visible to the naked eye, even in areas with moderate light pollution. Distant about 2.5 million light-years from Earth, its light reaching us today was emitted at the time when the first hominids were leaving Africa.

Despite the 2.5 million light-years that separate us, Andromeda is our closest galactic neighbor (if we omit the small satellite galaxies that orbit around ours, the Milky Way). So close that gravitational forces overcome the expansion of the universe, which will cause our collision with Andromeda in about 4 to 5 billion years.

Two small galaxies accompany it, its satellites: M32, compact and bright, set right against the disk, and M110, more diffuse and elongated, a little further off.