Completed the following sentence: In 1920 Heber Doust Curtis and Harlow Shapley participated in the
Great Debate on the nature of nebulae and galaxies, and the size of the universe.<unk> Great Debate on the nature of nebulae and galaxies, and the size of the universe. Shapley believed that distant nebulae were relatively small and lay within the Milky Way galaxy. Shapley believed that distant nebulae were relatively small and lay within the Milky Way galaxy. Curtis defended the now-accepted view that nebulae were farther away, and that other galaxies apart from the Milky Way therefore existed.