Whakaotihia te rerenga e whai ake nei: Ko te kitenga a Hubble o nga whetu rereke tekau ma tahi o Cepheid he tohu nui i roto i te mātauranga whetu. Mā te whakamahi i te pātahitanga o te wā Cepheid-Luminosity, i whakatau a Hubble i tētahi tawhiti o. Koinei te pūnaha tuatahi i tua atu i ngā Kapua o Magellanic kia whakaritea tōna tawhiti. (I haere tonu a Hubble i tēnei tukanga ki te Andromeda Galaxy me te Triangulum Galaxy). Ko tōna tawhiti ki te aorangi he tawhiti atu i te uara a Harlow Shapley o te 300,000 tau-marama mō te rahi o te ao nui. I roto i te pepa, i whakatau a Hubble i te "
Great Debate" o te tau 1920 i waenga i a Heber Curtis me Shapley mo te tauine o te ao me te ahua o te "nebula porohita". Kāore i roa ka mārama ko ngā pūngāwerewere katoa he whetū whetū kei waho atu i tō tātou ake Milky Way.