Which two classes of objects were critical to the Shapley-Curtiss Debate of 1920?
A)white dwarfs and red giants
B)open clusters and emission nebulae
C)globular clusters and spiral nebulae
D)emission nebulae and spiral nebulae
E)planetary nebulae and white dwarfs

Question

Quizplus · Accepted Answer

The Shapley-Curtiss Debate of 1920 focused on the nature of spiral nebulae and their place in the universe. Harlow Shapley argued that these nebulae were part of our own galaxy, while Heber Curtis believed that they were separate galaxies in their own right. The debate was ultimately resolved in favor of Shapley's view, with the discovery of Cepheid variable stars in the Andromeda Nebula in 1925 providing evidence that it was indeed a galaxy far beyond our own. The debate did not involve white dwarfs, red giants, open clusters, emission nebulae, or planetary nebulae. The two classes of objects that were critical to the Shapley-Curtiss Debate of 1920 were globular clusters and spiral nebulae. Shapley argued that the Milky Way galaxy was much larger than previously thought and that the globular clusters observed were distributed around a central core. On the other hand, Curtiss argued that the spiral nebulae were separate galaxies outside of the Milky Way. The debate ultimately led to a better understanding of the size of the universe and the nature of galaxies.

Which Two Classes of Objects Were Critical to the Shapley-Curtiss