Ku dhammee weedha soo socota: 1920 Heber Doust Curtis iyo Harlow Shapley waxay ka qaybgaleen
Dooda weyn ee ku saabsan dabeecadaha nebula iyo galaxiyada, iyo baaxada caalamka. Shapley waxa uu aaminsanaa in Nebulae-yada fog ay aad u yaryihiin isla markaana ay ku yaalaan gudaha galaxy-da Milky Way. Curtis wuxuu taageeray aragtida hadda la aqbalo ee ah in nebulae-yada ay ka fog yihiin, sidaas darteedna ay jiraan meerayaal kale oo aan ahayn Milky Way.