Space & Innovation

Why Does Easter Move Every Year?

The shifting date isn't simply a means of keeping Easter-egg hunters on their toes. Continue reading →

Easter this year lands on March 27, a relatively early date but perfect timing for anyone who needs a sugar fix since crashing shortly after Valentine's Day. Next year, April 16 marks the holiday.

Easter moves around year-to-year and can occur anywhere between March 22 and April 25. But why does it always fall on a different day within that five-week period? Surely, it's not simply to keep Easter-egg hunters on their toes?

The answer boils down to the difference between solar and lunar cycles. The ancient Egyptians first developed the solar calendar, which the Romans adopted, creating the Julian calendar. The Gregorian calendar succeeded the Julian calendar in Western Europe, and is the global standard today. The Hebrew calendar, however, follows the lunar cycles, as does the Islamic calendar.

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Easter is a religious holiday that commemorates the resurrection of Jesus Christ and always occurs on a Sunday. The preceding Friday marks Good Friday, the day of Jesus' death. And the night before that was the Last Supper, a feast for the Jewish holiday of Passover, according to the Bible. Given that it's a Jewish holiday, Passover naturally follows the Hebrew calendar.

The solar and lunar calendars don't sync up. The solar calendar is 365 days, five hours and 49 minutes, which is why February has a leap day every four years, while the lunar calendar only has 354 days. Reconciling the differences between the two has been attempted several times over the centuries, and different religious traditions have adopted their own timelines for observing the holiday.

In 325 A.D., the Council of Nicea convened and, in addition to hammering out the basic principles of their still flowering faith, attempted to set a standard for the celebration of the religious holiday. The council, composed of Christian bishops, decided that the church would observe Easter on the Sunday after the first full moon on or after the vernal equinox, known as the Paschal full moon. If the first full moon occurs on a Sunday, then the holiday is pushed back a week so that it still takes place after Passover.

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Although not universally observed at the time or the centuries that followed, the council established the basic practice for how Easter would be observed. They did make a number of errors in their calculations, however. The bishops fixed the date of the vernal equinox at March 21, though it occurs on March 20 today. Also, instead of relying on astronomical observations, the council instead devised a set of tables intended to following the lunar cycle that doesn't sync up with the phases of the moon.

That explains why the date of Easter moves every year. But the day most Western Christian churches celebrate Easter doesn't match the date of the holiday as observed by the Eastern Orthodox church. Again the discrepancy comes down to calendars. The Orthodox church still follow the Julian calendar, which is around 11 days behind the Gregorian calendar. Orthodox tradition observes Easter anywhere between April 4 and May 8. This year, it falls on May 1.

Attempts to modify the timing or set a fixed date for Easter have been welcomed by a number of Christian denominations, including the Catholic Church. One of the most recent efforts occurred in 1997 when representatives of various denominations convened in Aleppo, but failed to adopt a new standard.

March 1, 2012

-- This tomb, carved out of rock, could be "directly connected to Jesus' first followers, those who knew him personally, and to Jesus himself," according to researchers. Located beneath a modern condominium complex less than two miles south of the Old City of Jerusalem, this first-century burial, now named "patio tomb," is only 200 feet away from a second tomb, dubbed the "Jesus Family Tomb." Lying beneath a garden area in the same condominium complex, the burial was discovered in 1980. It contained 10 ossuaries, six of them inscribed with names associated with Jesus and his family. Critics dismissed the synchronicity of names as mere coincidence. "The object of our investigation was to determine whether the 'patio tomb,' still intact, might contain names or other evidence that would provide for us further data that might conceivably shed light on the adjacent 'garden tomb' with its intriguing cluster of names," James D. Tabor, professor and chair of religious studies at the University of North Carolina at Charlotte, wrote in a preliminary report published online in the "The Bible and Interpretation" website. He investigated the "patio tomb" with documentary filmmaker Simcha Jacobovici.

Photo: Jacobovici at the entrance of the sealed "patio tomb"

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In 2010, Tabor and Jacobovici entered the sealed tomb without actually opening it. They had obtained a license from the Israel Antiquities Authority to explore it through a minimally invasive procedure. Using 8-inch, custom-made diamond tooth drills, the team drilled two holes into the basement floor above the burial. A robotic arm was custom made so that it could be introduced into the tomb through the holes. The robotic arm not only had a main camera mounted on its tip, but a snake camera with a light that could extend about 4 feet beyond the main probe "to allow filming of several of the ossuaries that were deep in the recesses of the niches," said Tabor. The camera also had the capability of shooting laser beams to obtain micro-centimeter measurements.

Photo: Robotic arm

The probe was successful and the researchers were able to reach all areas of the tomb. Typical of Jerusalem in the period from 20 B.C. until 70 A.D, the tomb had a single central square chamber with a very shallow "standing pit" area. It contained nine carved burial niches with skeletal remains and several limestone ossuaries, or bone boxes.

Photo: Map of the tomb

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One ossuary was finely carved with a decoration which the researchers believe is "a clear image of a fish, complete with tail, fins, and scales." According to Tabor, it has "a stick-like human figure with an over-sized head coming out of its mouth." He interpreted the drawing as a representation of the biblical story of Jonah and the "big fish." In the earliest gospel materials, the "sign of Jonah," as mentioned by Jesus, has been interpreted as a symbol of his resurrection. "As Jonah was in the fish for three days and three nights, but emerged alive, Jesus would likewise emerge from the tomb/death," wrote Tabor. Jonah images only appear in the third and fourth centuries A.D., but never earlier, given the prohibition within Judaism of making images of people or animals. In this view, the fish would represent the oldest Christian art ever discovered, predating the earliest Christian symbol in the catacombs of Rome by at least 200 years. It would also represent the first archeological evidence related to faith in Jesus' resurrection from the dead -- "presumably by his contemporary 1st-century followers," said Tabor.

Image: CGI enhanced image of Jonah and the Big Fish

Another finely decorated ossuary contained an intriguing four-word Greek inscription. There are several ways to read the inscription, but according to Tabor, almost all of them have to do with resurrection, some linking directly to Jesus. The most likely readings are: "The Divine Jehovah raises up from (the dead)" or "The Divine Jehovah raises up to the Holy Place" or "God, Jehovah, Raise up! Raise up!" or "Lord, Jesus, Rise up! Rise up!" "We are dealing here with a family or clan that is bold enough to write out the holy name of God in a tomb, with a declaration about 'raising up' or resurrection -- something totally unparalleled in any of the 900 tombs from the period known in Jerusalem," wrote Tabor.

Photo: The unique four-line Greek inscription

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According to Tabor, the family buried in the tomb was undoubtedly Jewish. Apart from the Greek epitaph and fish image, "the style of the tomb, the ornamentation of the ossuaries, and everything else about it is nothing out of the ordinary," he said. Yet, taken together, the fish image and the inscription represents the earliest archaeological evidence of faith in Jesus' resurrection, the first witness to a saying of Jesus that predates the New Testament gospels, and the oldest Christian art ever discovered. "We are convinced that the best explanation for these unusual epigraphic features is its proximity to the Jesus family tomb," wrote Talbot. "What we apparently have is a family connected to the Jesus movement who reaches beyond the standard burial norms of the Jewish culture of the period to express itself individually in these unique ways," he said.

Photo: Complete Findings from the Patio Tomb

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