For years, astronomers have observed the strange motion of Andromeda, the Milky Way’s closest large galactic neighbor. While ...

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

For more than a century, astronomers have watched in astonishment as the Andromeda galaxy ignored the grand flow of cosmic expansion and hurtled straight toward the Milky Way. While almost every other ...

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

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

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 ...

A flat plane of dark matter beyond the Local Group may explain why nearby galaxies move away from us instead of falling ...

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 ...