For further information on Christian tourism and Holy Land Tours to Israel contact Travelujah.Christians visiting the Holy Land in the spring sometimes fail to appreciate the link between Passover and Easter: Jesus came to Jerusalem in April circa 34, making his triumphal entry on the Sunday of the last fateful week of his life, in order to offer a Passover sacrifice at Herod's magnificent newly-built Temple. He celebrated the Passover seder banquet that Thursday night, an event commonly referred to as the Last Supper. Returning with his apostles to their encampment at Gethsemane on the nearby Mount of Olives, he was arrested that evening after being betrayed by Judas. On Friday, the holy day of Passover, he was tried and then crucified. His corpse was hurriedly placed in a new sepulcher or family tomb belonging to Joseph of Arimathea near to the Skull Hill execution grounds so as not to violate the Sabbath that began Friday shortly before sundown. Sunday morning it was discovered that the rolling stone sealing Jesus' tomb had been shifted, and the sepulcher was empty. Jesus had arisen.Thus Passover and Easter began on the same date. But Christianity, the daughter religion of Judaism, was anxious to disassociate itself from its sources, and so established a new formula to calculate Easter that was independent of Passover. Judaism celebrates the holiday (called Pessah in Hebrew) on the full moon of the seventh month of Nisan in commemoration of the Hebrews' exodus from slavery in Egypt. Since Hebrew days begin and end at sundown, Passover begins at sundown on the preceding day. Thus this year Jews across the world celebrate the seder on Friday, April 6 after sunset. In rejecting the Jewish lunar liturgical calendar as the basis for Easter and other Christian moveable feasts, the Church fathers still relied on astronomical occurrences. In the Western Church, including both Roman Catholic and Protestant denominations, Easter is calculated as the first Sunday after the paschal full moon that occurs on or after the vernal equinox. If the full moon falls on a Sunday, then Easter is the following Sunday. The holiday can occur anywhere between March 22 and April 25, and this year falls on Sunday, April 8. The Western church does not however use the astronomically correct date for the vernal equinox but the arbitrarily fixed date of March 21. And by full moon it does not mean the astronomical full moon but the "ecclesiastical moon," which is based on tables created by the church. These constructs allow the date of Easter to be calculated in advance rather than determined by actual astronomical observances, which are naturally less predictable. While the Eastern or Orthodox Churches use the same formula to calculate Easter, they base the date on a slightly different calendar-the Julian calendar rather than the revised Gregorian calendar that was adopted by Pope Gregory XIII in 1582 to correct for slippage in the seasons caused by the failure to adjust the calendar by an extra day every fourth leap year. Consequently, both the Western and Eastern churches only occasionally celebrate Easter on the same day. This year the Orthodox church celebrates Easter on Sunday, April 15 - one week after Roman Catholics and Protestants. Unlike the Western Church, the Eastern Church sets the date of Easter according to the astronomical full moon and the actual equinox as observed along the meridian of Jerusalem, site of the crucifixion and resurrection.Gil Zohar is a Canadian born Israeli tour guide and journalist and writes regularly for Travelujah, the leading Christian social network focused on travel to the Holy Land. People can learn, plan and share their Holy Land tour and travel experiences on Travelujah.