▁of ▁which ▁is ▁histor ically ▁known ▁as ▁the ▁" first ▁point ▁of ▁A ries ". ▁The ▁first ▁ 3 0 ° ▁along ▁the ▁e cli ptic ▁is ▁nomin ally ▁designated ▁as ▁the ▁z od iac ▁sign ▁A ries , ▁which ▁no ▁longer ▁falls ▁within ▁the ▁proxim ity ▁of ▁the ▁const ell ation ▁A ries ▁since ▁the ▁effect ▁of ▁pre cess ion ▁is ▁to ▁move ▁the ▁v ernal ▁point ▁through ▁the ▁back drop ▁of ▁visible ▁const ell ations ▁( it ▁is ▁currently ▁located ▁near ▁the ▁end ▁of ▁the ▁const ell ation ▁P is ces , ▁having ▁been ▁within ▁that ▁const ell ation ▁since ▁the ▁ 2 nd ▁century ▁AD ). ▁The ▁subsequent ▁ 3 0 ° ▁of ▁the ▁e cli ptic ▁is ▁nomin ally ▁designated ▁the ▁z od iac ▁sign ▁T aur us , ▁and ▁so ▁on ▁through ▁the ▁twelve ▁signs ▁of ▁the ▁z od iac ▁so ▁that ▁each ▁occup ies ▁ 1 / 1 2 th ▁( 3 0 ° ) ▁of ▁the ▁z od iac ' s ▁great ▁circle . ▁Z od iac ▁signs ▁have ▁never ▁been ▁used ▁to ▁determine ▁the ▁boundaries ▁of ▁astronom ical ▁const ell ations ▁that ▁lie ▁in ▁the ▁vic inity ▁of ▁the ▁z od iac , ▁which ▁are , ▁and ▁always ▁have ▁been , ▁irregular ▁in ▁their ▁size ▁and ▁shape . ▁ ▁The ▁convention ▁of ▁meas uring ▁cel est ial ▁longitude ▁within ▁individual ▁signs ▁was ▁still ▁being ▁used ▁in ▁the ▁mid - 1 9 th ▁century , ▁but ▁modern ▁astronom y ▁now ▁numbers ▁degrees ▁of ▁cel est ial