Tuhia he tohutoro mō tēnei wāhanga - I mua i te mōhiotanga o ngā aorangi kōhurihuri i waho atu i tō tātou aorangi Milky Way, i kīia rātau ko ngā "nebulae kōhurihuri". Ko te pātai mēnā he whetū motuhake ēnei ahanoa, he mea motuhake rānei i te Milky Way, he momo kapua rānei kei roto i tō tātou ake whetū, ko te kaupapa o te Kōrero Nui
o 1920, i waenga i a Heber Curtis o Lick Observatory me Harlow Shapley o Mt. Ko te Whare Tirohanga o Wilson. I te tīmatanga o te tau 1923, ka kite a Edwin Hubble i ngā tāupe Cepheid i roto i ngā nebulae porohita maha, tae atu ki te "Andromeda Nebula", e tohu ana he, he tino, he whetū katoa i waho atu i a tātou. Ko te kupu "nebula porohita" kua kore e whakamahia.