▁left ▁them ▁travel ing ▁by ▁night ▁across ▁open ▁water . ▁Here ▁the ▁sail ors ▁would ▁use ▁the ▁locations ▁of ▁particular ▁stars , ▁especially ▁those ▁of ▁the ▁const ell ation ▁Urs a ▁Major , ▁to ▁orient ▁the ▁ship ▁in ▁the ▁correct ▁direction . ▁ ▁Writ ten ▁records ▁of ▁navigation ▁using ▁stars , ▁or ▁cel est ial ▁navigation , ▁go ▁back ▁to ▁H omer ' s ▁Od ys sey ▁where ▁Cal y ps o ▁tells ▁Od ys se us ▁to ▁keep ▁the ▁Bear ▁( U rs a ▁Major ) ▁on ▁his ▁left ▁hand ▁side ▁and ▁at ▁the ▁same ▁time ▁to ▁observe ▁the ▁position ▁of ▁the ▁P lei ades , ▁the ▁late - setting ▁Bo ö tes ▁and ▁the ▁Or ion ▁as ▁he ▁sa iled ▁east ward ▁from ▁her ▁island ▁O gy gia ▁travers ing ▁the ▁Ocean . ▁ ▁The ▁Greek ▁poet ▁Ar atus ▁wrote ▁in ▁his ▁Ph ain omena ▁in ▁the ▁third ▁century ▁BC ▁detailed ▁positions ▁of ▁the ▁const ell ations ▁as ▁written ▁by ▁E ud ox os . ▁The ▁positions ▁described ▁do ▁not ▁match ▁the ▁locations ▁of ▁the ▁stars ▁during ▁Ar atus ' ▁or ▁E ud ox os ' ▁time ▁for ▁the ▁Greek ▁main land , ▁but ▁some ▁argue ▁that ▁they ▁match ▁the ▁sky ▁from ▁Cre te ▁during ▁the ▁Bron ze ▁Age . ▁This ▁change ▁in ▁the ▁position ▁of ▁the ▁stars ▁is ▁due ▁to ▁the ▁wob ble ▁of ▁the ▁Earth ▁on ▁its ▁axis ▁which ▁affect s ▁primarily ▁the ▁pole ▁stars . ▁Ar ound ▁ 1 0 0 0 ▁BC ▁the ▁const ell ation ▁D