️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️ Using the Cepheid Period-Luminosity relationship, Hubble determined a distance of. ąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąąą (Hubble continued this process with the Andromeda Galaxy and the Triangulum Galaxy) <unk> (Hubble continued this process with the Andromeda Galaxy and the Triangulum Galaxy). ️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️ <unk> <unk> <unk>
1920 Great Debate between Heber Curtis and Shapley over the scale of the universe and the nature of the "spiral nebula". ️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️<unk>️