Rubuta ci gaba don wannan sakin layi - A cikin 1920, Babban Muhawarar
tsakanin Harlow Shapley da Curtis ya faru game da yanayin Milky Way, nebulae na karkace, da girman sararin samaniya. Don tallafawa da'awarsa na Babban Andromeda Nebula kasancewa, a zahiri, wani galaxy na waje, Curtis kuma ya lura da bayyanar da hanyoyi masu duhu a cikin Andromeda wanda yayi kama da gajimare a cikin galaxy ɗinmu, da kuma lura da tarihi na mahimmancin Doppler na Andromeda Galaxy. A cikin 1922 Ernst Öpik ya gabatar da wata hanya don kimanta nisan Andromeda ta amfani da saurin taurari da aka auna. Sakamakonsa ya sanya Andromeda Nebula nesa da galaxy a nesa da kimanin. Edwin Hubble ya warware muhawara a 1925 lokacin da ya gano taurari masu canzawa na Cepheid na farko a kan hotunan taurari na Andromeda. An yi waɗannan ne ta amfani da na'urar hangen nesa ta Hooker, kuma sun ba da damar sanin nisan Great Andromeda Nebula. Ƙididdigar da ya yi ta nuna cewa wannan ba tarin taurari da iskar gas ba ne da ke cikin damin taurari na mu, amma wani damin taurari ne dabam da ke da nisa sosai daga damin taurari na Milky Way.