Christian History Home > 2004 > Why does Easter's date wander?
LENT & HOLY WEEK
Why does Easter's date wander?
This week, as they so often do, my Sunday School class of bright 12- and 13-year-olds posed a tough question: why did Easter fall on Evan's birthday last year, but it's falling on Abby's birthday this year? Though I couldn't answer on the spot, I knew I had a secret weapon back at the office—saved for just such an occasion: a short article by Farrell Brown, a retired chemistry professor with an interest in the historical interactions between science and religion. Here, as a public service for those still scratching their heads over the calendrical wandering of Easter, is Dr. Brown's answer to my Sunday School kids' question—and thrown in for free, the story of why Easter dates still differ in different parts of the world:
The date of Easter Sunday, a so-called movable feast day in the Christian Church year, may seem mysterious to many who celebrate it. There are 35 possible dates in the spring season (northern hemisphere) for celebrating a one-time event.Â Why this wandering? The answer comes from decisions made several centuries after Christianity's inception.
And why do most Eastern Orthodox Christian Churches observe Easter occasionally on the same Sunday as the rest of Christendom and at other times as much as five weeks later? This answer lies primarily in how different people reacted to a centuries-old papal decree.Â Â Â Â
Our first stop on this tour of the wandering Easter is a quick study of how calendars were used in the Biblical lands around 30 A.D. Although the Julian or solar-based calendar of the Roman Empire had been in place since 45 B.C., it did not supplant the lunar calendar that was the chart and compass of 2,000 years of Jewish history. (A lunar year is 12 lunar cycles of 29.53 days each or 354.36 days while a Julian year is 365.25 days with a leap day every four years.) The Julian calendar functions by having three years of 365 days and one year of 366 days every four years.
The incongruence of the two calendars had marred historical recordings in the Eastern Mediterranean and environs since the dual systems began. And to add to the confusion, Jesus' followers had failed to record the exact date of their Lord's resurrection. Many of those first believers expected Jesus to return soon, a hope that (some scholars believe) rendered such anniversaries unimportant for them. For these reasons, a single, universally accepted date for the event's celebration had little to no chance.
The Nicean accord
Three hundred years later in the reign of the Roman Emperor Constantine, Christianity was beginning to spread though out the Empire. Since any self-respecting religion was expected to have its religious festivals and days of observance, a date for celebrating Easter now became a priority. In fact, this was one of eight major topics considered by priests and bishops at the church's first Ecumenical Council in 325, in Nicea (present-day Turkey). One unanimously accepted canon guaranteed that Easter would never fall on the beginning the Jewish Passover, perhaps reflecting Christian animosity towards the Jewish people for their perceived role in Jesus' death.
However, each church group present at Nicea seemed to have a different opinion on the matter of Easter's date. The biggest division was that between the Eastern churches of Antioch and Syria, which still relied on the Jewish or lunar calendar for determining the date of Easter, and the Western churches of Alexandria and Rome, which employed the efficient solar calendar. The resulting accord, as commonly stated, was that Easter shall fall on the first Sunday following the first full moon following the spring equinox. (The spring equinox is one of the two times in the year when the sun crosses the celestial equator and the length of day and night are approximately equal.)
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