The twentieth century opened with a major unresolved question among astronomers. This was the subject of the famous Shapley-Curtis debate. What was this question?
A) How old is the Milky Way Galaxy?
B) What is the nature of dark matter?
C) Is general relativity true?
D) Is the Milky Way Galaxy the whole universe, or only one of many galaxies?

Question

Quizplus · Accepted Answer

The Shapley-Curtis debate centered on whether the Milky Way was the entirety of the universe or just one of many galaxies. Harlow Shapley argued for the former, while Heber Curtis supported the latter view, which is now known to be correct.

The Twentieth Century Opened with a Major Unresolved Question Among