Asked by qwerty

What observations were used by Edwin Hubble to show that the universe is expanding?

- The distance to a galaxy is proportional to its luminosity.
- The distance to a galaxy is inversely proportional to its apparent size.
- The distance to a galaxy is proportional to its velocity relative to the Milky Way.
- The distance to a galaxy is proportional to its rotational velocity.
Answered by Anonymous
The distance to a galaxy is proportional to its velocity relative to the Milky Way.
Answered by Ringo
The fact that the distance to a galaxy is proportional to its velocity relative to the Milky Way indicated to Hubble that the universe is expanding.