Completed the following sentence: In 1920 he was appointed director of the Allegheny Observatory. <unk> <unk> <unk>
The Great Debate with Harlow Shapley (also called the Shapley<unk>Curtis Debate) on the nature of nebulae and galaxies, and the size of the universe. Curtis defended the now-accepted view that other galaxies apart from the Milky Way existed.<unk> Curtis advocated the now-accepted view that other galaxies apart from the Milky Way existed.