How Fast Is Andromeda Galaxy Approach?

The Andromeda Galaxy is approaching the Milky Way at 110 km/s — on a long-term collision course with our own galaxy. But galaxies are so empty that very few stars will actually hit; the two will instead merge into a single new galaxy with little real disruption.

The light from Andromeda you see tonight took an enormously long time to reach you — meaning everything you see of the galaxy is from very long ago by the time the photons arrive.

• Long-term collision course with our galaxy
• Mostly empty — stars won't actually hit