Question

Galaxies look stationary, so why do scientists say that they rotate?​

Answer 1

Hey mate!

Galaxies do indeed rotate. It's because galaxies are unimaginably huge. ... An object traveling at high speed across a very long distance appears to be moving slowly when viewed from far away.

Happy to help :)

Answer 2

Galaxies do indeed rotate because galaxies are so huge. An object coming very fast from a very far, appears to be moving slowler when seen from far away.