Qoraal sii socota faqradan - Cepheids waxaa si dhakhso leh loogu ogaadey meerayaasha kale, sida Andromeda (gaar ahaan Edwin Hubble 1923<unk>24), waxayna noqdeen qayb muhiim ah oo ka mid ah caddaynta in "Nebulae spiral" ay yihiin meerayaal madaxbannaan oo ku yaal meel ka baxsan Milky Way. Hadaba, Leavitt waxa uu helay waxa uu weligiis badali lahaa aragtideena caalamka, maadaama uu ku dhiirigeliyay Harlow Shapley in uu qoraxdeena ka dhaqaajiyo bartamaha galaxy-da "Dooda Weyn"
" iyo Edwin Hubble si ay ugu guuraan Galaxy-deena bartamaha caalamka.