▁( its elf ▁based ▁on ▁the ▁Egypt ian ▁lit urg ical ▁lun ar ▁calendar ▁put atively ▁introduced ▁to ▁the ▁Israel ites ▁by ▁Mos es ▁in ▁the ▁ 1 3 th ▁century ▁BC , ▁and ▁still ▁used ▁today ▁by ▁the ▁Sam ar it ans ). ▁The ▁official ▁" J ew ish " ▁Pass over ▁in ▁contrast ▁was ▁determined ▁by ▁a ▁Jewish ▁calendar ▁reck oning ▁which ▁had ▁been ▁modified ▁during ▁the ▁Bab yl onian ▁ex ile ▁in ▁the ▁ 6 th ▁century ▁BC . ▁This ▁modified ▁Jewish ▁calendar ▁is ▁in ▁use ▁among ▁most ▁Jews ▁today . ▁One ▁basic ▁difference ▁lies ▁in ▁the ▁determ ination ▁of ▁the ▁first ▁day ▁of ▁the ▁new ▁month : ▁while ▁the ▁Sam ar it ans ▁use ▁the ▁calculated ▁( because ▁by ▁definition ▁invisible ) ▁new ▁moon , ▁main stream ▁Jews ▁use ▁the ▁first ▁observation ▁of ▁the ▁thin ▁cres cent ▁of ▁the ▁w ax ing ▁moon ▁which ▁is ▁on ▁average ▁ 3 0 ▁hours ▁later . ▁The ▁other ▁basic ▁difference ▁lies ▁in ▁the ▁fact ▁that ▁the ▁Sam ar itan ▁calendar ▁uses ▁a ▁sun r ise - to - sun r ise ▁day , ▁while ▁the ▁official ▁Jewish ▁calendar ▁uses ▁a ▁sun set - to - sun set ▁day . ▁Due ▁to ▁these ▁differences , ▁the ▁Sam ar itan ▁Pass over ▁is ▁normally ▁one ▁day ▁earlier ▁than ▁the ▁Jewish ▁Pass over ▁( and ▁in ▁some ▁years ▁two ▁or ▁more ▁days ▁earlier ). ▁The ▁cru c if ix ion ▁year ▁of ▁Jesus ▁can ▁then ▁be ▁calculated ▁by ▁asking ▁the ▁question ▁in ▁which ▁of ▁the