Duba wurin da ke ƙasa sannan ka amsa tambayar daga baya a cikin harshe ɗaya kamar yadda wurin yake:  Passage: Girkawa masu binciken taurari sun yi amfani da samfurin da aka yi amfani da shi a cikin ƙarni tare da ra'ayin eccentric (mai karɓa wanda yake dan kadan daga tsakiyar duniya), wanda ya fi tsufa. A cikin hoton, cibiyar deferent ba Duniya ba ce amma wurin da aka yi alama X, yana mai da shi eccentric (daga Helenanci ἐκ ec- ma'ana "daga", da κέντρον kentron ma'ana "cibiyar"), daga inda wurin ya sami sunansa. Abin takaici, tsarin da yake samuwa a lokacin Ptolemy bai dace da lura ba, ko da yake an inganta shi sosai a kan tsarin Hipparchus. Mafi mahimmanci girman madauki na duniyar duniyar (musamman na Mars) zai zama ƙarami, kuma wani lokacin ya fi girma, fiye da yadda ake tsammani, wanda ke haifar da kuskuren matsayi har zuwa digiri 30. Don ya magance wannan matsalar, Ptolemy ya ƙirƙiro ma'auni. Equant wani wuri ne kusa da tsakiyar duniyar duniyar duniyar wanda, idan kun tsaya a can kuma ku duba, cibiyar duniyar duniyar za ta kasance a koyaushe tana motsawa a cikin sauri; duk sauran wurare za su ga saurin sauri, kamar yadda yake a duniya. Ta hanyar amfani da daidaito, Ptolemy ya yi iƙirarin kiyaye motsi wanda ya kasance mai daidaituwa da zagaye, kodayake ya rabu da manufa ta Platonic na daidaitaccen zagaye. Sakamakon tsarin, wanda daga bisani ya zama karɓaɓɓu a yamma, yana da wuya ga masu nazarin sararin samaniya na zamani; kowace duniyar ta buƙaci wani epicycle mai juyawa a kan wani mai juyawa, wanda ya dace da wani nau'i wanda ya bambanta ga kowane duniyar. Ya yi hasashen motsi na sama daban-daban, gami da farkon da ƙarshen motsi na baya, zuwa cikin mafi girman kuskuren digiri 10, ya fi kyau fiye da ba tare da daidaito ba.  Tambaya: Mene ne mutanen da suka yi amfani da deferent da epicycle model?
Masanan taurari na Girka