<prompt> Bhala okuqhubekayo kwalesi sigaba - Ngo-1920 wamiswa njengomqondisi we-Allegheny Observatory. Ngawo lowo nyaka wabamba iqhaza kwi-Great Debate  <response>: noHarlow Shapley obizwa nangokuthi i- Shapley Curtis Debate ngesimo sama-nebula nemithala, kanye nosayizi wendawo yonke. UCurtis wayemelela umbono osamukelwayo manje wokuthi kwakukhona neminye imithala ngaphandle koMzila Wobisi. 