<prompt> Qedela le nkulumo elandelayo: Ngaphambi kokuba kuqondwe ukuthi kunezinkanyezi eziyindilinga ngaphandle komthala wethu i-Milky Way, ngokuvamile zazibizwa ngokuthi ama-spiral nebula. Umbuzo wokuthi ngabe izinto ezinjalo zazingama-galaxy ahlukene azimele eMilky Way, noma uhlobo lwe-nebula olukhona ngaphakathi komthala wethu, wawuyisihloko se-  <response>: I-Great Debate ka-1920, phakathi kukaHeber Curtis waseLick Observatory noHarlow Shapley waseMt. Indawo Yokubuka Izinkanyezi iWilson. Kusukela ngo-1923, u-Edwin Hubble waqaphela izinto eziguquguqukayo ze-Cephid ezinama-nebula amaningana avundlile, kuhlanganise nalawo abizwa ngokuthi i-Andromeda Nebula, okufakazela ukuthi empeleni, ayizinkanyezi eziphelele ezingaphandle kwezethu. Igama elithi spiral nebula selingasasetshenziswa. 