From mcnees@mastodon.social on Mastodon: Astronomers Harlow Shapley and Heber Curtis held their "Great Debate" over the scale of the Universe # OTD in 1920. Curtis argued that our Milky Way was one of many galaxies. Shapley, on the other hand, claimed the Universe was just one galaxy, with our sun far from its center. https:// archive.org/details/scaleofuni verse00shap/page/172/mode/2up