The event that settled the Shapley-Curtis debate about "spiral nebulae" was
A) Edwin Hubble measuring the distance to the Andromeda Galaxy.
B) Arno Penzias and Robert Wilson detecting the cosmic microwave background radiation.
C) Albert Einstein showing that gravity can bend the path of light.
D) Edwin Hubble showing that the universe was expanding.

Question

Quizplus · Accepted Answer

Edwin Hubble's measurement of the distance to the Andromeda Galaxy provided conclusive evidence that it was far outside the Milky Way, thus resolving the Shapley-Curtis debate by showing that spiral nebulae were indeed other galaxies.

The Event That Settled the Shapley-Curtis Debate About "Spiral Nebulae