Harlow Shapley. Participant in the `Great Debate' in 1920. Shapley argued that our Galaxy was large, our Sun was offset greatly from the center, and he did not endorse spiral nebulae as external galaxies. Both Shapley and Curtis were incorrect on the first point (Shapley guessed too large, Curtis too small) and Shapley was also incorrect on the last point. That Shapley was correct in the second point has changed mankind's view of our place in the universe.