A sheet of dark matter lying beyond the boundary of the Local Group is responsible for this.

For more than a century, astronomers have watched in astonishment as the Andromeda galaxy ignored the grand flow of cosmic ...

A vast, flat sheet of dark matter may solve the long-standing mystery of why our neighboring galaxy Andromeda is speeding ...

On a clear night, the Milky Way and the Andromeda galaxy look like close neighbors. In space, they really are.

Andromeda is also a flattened spiral like the Milky Way, but it's twice as large — 220,000 light-years across versus 105,000 for the Milky Way — and crammed with a trillion suns. Can you even begin to ...

Forbes contributors publish independent expert analyses and insights. An award-winning reporter writing about stargazing and the night sky. This illustration shows a stage in the predicted merger ...

Andromeda and GEM now determine how ads are selected, ranked, and sequenced across Meta. Here’s what changed and what drives ...

The Andromeda Galaxy (M31) is the largest member of the Milky Way’s gang of galactic neighbors, known as the Local Group. With around a trillion suns worth of mass, Andromeda’s gravitational influence ...

Jackson Ryan was CNET's science editor, and a multiple award-winning one at that. Earlier, he'd been a scientist, but he realized he wasn't very happy sitting at a lab bench all day. Science writing, ...