Kammala wannan jumla: A cikin 1920 Heber Doust Curtis da Harlow Shapley sun shiga cikin
Babban muhawara a kan yanayin nebulae da galaxies, da kuma girman duniya. Shapley ya gaskata cewa nebulae masu nisa sun kasance ƙananan ƙananan kuma suna cikin galaxy Milky Way. Curtis ya goyi bayan ra'ayin da aka yarda da shi yanzu cewa nebulae sun fi nisa, kuma saboda haka akwai wasu taurari banda Milky Way.