Astronomers know the universe is expanding because:
A)everything is moving away from us.
B)all stars are moving away from us.
C)most galaxies are moving away from us.
D)galaxies farther away are moving away from us faster.
E)there is a cosmic microwave background.

Question

Quizplus · Accepted Answer

Galaxies farther away from us are moving away from us faster, which indicates that the universe is expanding. This is known as Hubble's Law. The observation that galaxies farther away from us are moving away from us faster is known as Hubble's law, and it provides evidence that the universe is expanding.

Astronomers Know the Universe Is Expanding Because