The Andromeda Galaxy

The light that made this image left the Andromeda Galaxy 2.5 million years ago — before modern humans existed. It’s the nearest large galaxy to our own, and at six times the apparent width of the full Moon, it’s the most distant object visible to the naked eye. What you’re looking at is a trillion stars, sweeping dust lanes, and two satellite galaxies (M32 and M110) caught in its gravitational pull. Andromeda is approaching the Milky Way at 110 km/s. In about 4.5 billion years, the two will merge.