Pedzisa mutsara unotevera: Muna 1920 akagadzwa kuva mutungamiriri weAllegheny Observatory. Mugore rimwe chetero akapindawo mu
Great Debate naHarlow Shapley (anonziwo Shapley-Curtis Debate) pamusoro pechimiro chema nebulae nemapoka enyeredzi, uye kukura kwechisiko chose. Curtis akatsigira pfungwa yava kugamuchirwa iye zvino yokuti kune mamwe mapoka enyeredzi kunze kweGwara Renzou.