Milky Way set for head-on crash with Andromeda galaxy

Posted by Emma Woollacott


The Milky Way, says NASA dryly, is set to get 'a major makeover' in the process. But while our sun will be flung into a new region of the galaxy, it and the rest of the solar system are in no danger of being destroyed. This is because the stars are far enough apart to make collisions highly unlikely.


Andromeda, also known as M31, is now 2.5 million light-years away, but is inexorably falling toward the Milky Way under the pull of gravity between the two galaxies and the invisible dark matter that surrounds them both.

Another two million years later, the two galaxies will merge and reshape into a single ellipse.


The stars in both galaxies will be thrown into different orbits around the new galactic center, and simulations show that our solar system will probably end up much farther from the galactic core than it is today.

To make matters more complicated, M31's small companion, the Triangulum galaxy, M33, will join in the collision and perhaps later merge with the M31/Milky Way pair. Indeed, there's a small chance that M33 will hit the Milky Way first.

While the encounter between Andromeda and the Milky Way has been predicted for a long time, it wasn't known whether there'd be a narrowmiss, a glancing blow or a head-on smash, as until now it's proved impossible to measure M31’s tangential motion.


"In the worst-case-scenario simulation, M31 slams into the Milky Way head-on and the stars are all scattered into different orbits," says Gurtina Besla of Columbia University in New York.
