106 years ago today, the Smithsonian Museums in the nation's capital held the first of its Great Debate series, with the topic being whether spiral galaxies and nebulae were relatively small and part of the Milky Way. Arguing in the affirmative was Harlow Shapely, head of the Harvard College Observatory. Arguing in the negative was astronomer Heber Curtis. A year later the two sides of the debate were presented and expanded on in independent technical papers under the title "The Scale of the Universe." READ more about the Great Debate... (1920)
