Whakaotihia te rerenga e whai ake nei: I mua i te mōhiotanga kei waho atu i to tatou Milky Way, ko nga whetū porohita, i kiia rātau ko "nebulae porohita". Ko te pātai e pā ana ki te mea i ngā ahanoa pērā i tupuni motuhake motuhake o te Milky Way, ranei te momo o te nebula tīariari i roto i to tatou ake tupuni, ko te kaupapa o te
Te Tohe Nui o te tau 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 to tatou ake. Ko te kupu "nebula porohita" kua kore e whakamahia.