Hubble was able to prove that galaxies are very far away because he...

A. measured the relative size of galaxies
B. built the first space telescope
C. discovered Cepheid variables in galaxies
D. measured the speed of galaxies



Answer :

Final answer:

Hubble proved galaxies are far away by discovering Hubble's Law and the expansion of the Universe.


Explanation:

Edwin Hubble measured the distances to galaxies and found a relationship known as Hubble's Law, which states that the farther a galaxy is, the faster it is moving away. By comparing distance estimates with recession velocities, he concluded that the universe is expanding.


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