How do astronomers know about the future collision of Andromeda and the Milky Way?(1 point)

Question

Responses

The two galaxies have collided previously.
The two galaxies have collided previously.

The Milky Way has changed course to head toward Andromeda.
The Milky Way has changed course to head toward Andromeda.

Astronomers have observed their movements over time.
Astronomers have observed their movements over time.

All galaxies will collide at some point.

Answer 1

Astronomers have observed their movements over time.