Orbits of Andromeda and Milky Way Galaxy About Each Other

[RJ Emery]

The orbits of the Magellanic Clouds about the Milky Way Galaxy have apparently been determined, and the two dwarf irregular galaxies are now about as close as they will get to the MW in their 2.2 billion year orbit. See p. 42 of "Our Growing, Breathing Galaxy" by Wakker and Richter, Scientific American, January, 2004, pp. 38-47.

If the orbit of the Magellanic Clouds can be determined with modern observing technology, what of the Andromeda Galaxy? Is it known when and how close Andromeda and the MW will meet at their closest approach?

 

[marcus]

I don't know that the trajectory of Andromeda relative to Milky has been determined accurately enough to say.

A couple of years ago I read a prediction that Andromeda would actually pile into Milky.

Galaxies do collide---there are pictures of it happening. And it tends to mess both of them up some. But for the most part it does not mean that individual stars collide and it wouldn't necessarily mess the solar system.

You may well know all this and more---may know more than I do.

I remember the approach speed as 50 km/second, and the time it would take before Andromeda gets here was estimated in hundreds of millions of years.
I don't know that there is a firm prediction of collision

(the problem would be that the radial speed could be determined pretty well but lateral motion would be very hard if not impossible to detect---Andromeda galaxy being so far away)