Uncovering the Milky Way’s traumatic past

Published in Horizon, 8 Apr 2015

Astrophysicists in Germany are piecing together the final parts of a map that will help tell us whether the Milky Way suffered a massive collision with another galaxy, billions of years ago.

Our galaxy is pretty average in the scheme of things. Like most other stars in the universe, the stars in the Milky Way are arranged in a wispy, spiral-shaped disc. Our sun is about half way out, on the rim of what is known as the Orion Arm.

Even so, there are some peculiarities with the Milky Way. Simple theories of galaxy formation suggest that its disc of stars ought to be perfectly flat, not puffy as it appears through telescopes. […]

The rest of this article is available here.