For nearly a century, astronomers have known that the universe is expanding. Most galaxies are carried outward with the flow ...

For years, astronomers have observed the strange motion of Andromeda, the Milky Way’s closest large galactic neighbor. While most galaxies in the universe are receding due to the expansion of space, ...

Astronomers have long known that the Andromeda galaxy, aka Messier 31, a swirling city-state of a trillion stars — plus all the accouterments of gas, dust, dark matter and black holes — is rumbling ...