The chances of colliding with a star are a million to one

18 February 2009

My recent mentions of the eventual merger/collision of the Milky Way and Andromeda galaxies, giving rise to “Milkomeda”, has prompted some reader questions about the likelihood of a star from Andromeda colliding with the Sun, during the “merger”.

One thing to remember is the collision is billions of years away, should it even happen, but the chances of stars from either galaxy colliding are extremely remote given the astronomical distances between them:

As with all such collisions, it is unlikely that objects such as stars contained within each galaxy will actually collide, as galaxies are in fact very diffuse – the nearest star to the Sun is in fact almost thirty million solar diameters away from the Earth. (If the sun were scaled to the size of an American quarter, 24.26 mm (0.955 in), the next closest quarter/star would be 700 km (475 miles) away.)

Originally published Wednesday 18 February 2009.