HOW THE DATE OF EASTER IS DETERMINED

The Paschal Full Moon Determines the Date of Easter

Hello My Friend and Welcome. 

We continue our Lenten — Easter Series with a discussion of how the date of Easter is determined. I recall, as a child, overhearing adults say, “Isn’t Easter early this year?” or “Easter sure is late this year.” I found this very confusing. What did they mean late or early? Easter came the same time as any other year…on Sunday. 

Easter is, and always has been, a movable Feast. In many parts of the world Easter is known as the Pascha, from the Greek word for Pesach, or Passover. As we know from the Bible, Jesus was arrested and executed on a Friday during the Jewish Passover week. And, as we also know, Easter is a celebration of his Resurrection on the following Sunday. So, in my defense, I was partially right. It always comes on Sunday…at least it does now. 

EASTER, PASSOVER AND THE QUARTODECIMAN CONTROVERSY

Like our Easter, Passover is a movable, seven-day Feast which begins Nisan 15 (at sundown Nisan 14) and is determined by the phases of the moon. The Early Church was comprised mostly of Jews and so they continued to follow the Hebrew calendar and celebrated the day of Resurrection following Passover. However, since Passover can fall on any day of the week, this meant that the Resurrection was not always celebrated on a Sunday. And that’s when things started getting sticky. 

The result was what has come to be called the “Quartodeciman Controversy,” from the Latin quatro decima or fourteen. The Controversy boils down to a simple question: Must the Resurrection be celebrated on a Sunday? The writings of the Church Father, Irenaeus, state that Polycarp, Bishop of Smyrna, kept the Feast on the fourteenth day of the moon, whatever day of the week that might happen to be. In other words, he celebrated the Resurrection on the day of Crucifixion. Keep in mind that, like Ignatius of Antioch, Polycarp was a disciple of the Apostle John, and he claimed the tradition came from St. John himself. Meanwhile, the Roman and Alexandrian churches began extending the Lenten fast until the Saturday after the 14^th and celebrated the Resurrection the following day, on Sunday. Though argued and debated, the issue was never conclusively resolved.

Polycarp, Bishop of Smyrna

RELYING UPON THE HEBREW CALENDAR

We find both practices continuing as we move forward in time. But, regardless of whether you celebrated the Day of Resurrection or the Sunday of Unleavened Bread, you were still dependent upon the Jewish calendar to establish the date of Nisan 14. By the later 3rd century the Church had become thoroughly gentile and some Christians expressed dissatisfaction with the custom of relying on the Jewish community to determine the date of a Christian Feast. They also complained that the observance of a full moon varied between the northern and southern hemispheres, leading to errors.  

Anatolius of Laodicea in the later 3rd century wrote, “Those who place the first lunar month of the year in the twelfth zodiacal sign before the spring equinox and fix the Paschal fourteenth day accordingly, make a great and indeed an extraordinary mistake.” An ancient paschal table confirms these complaints, indicating that Jews in some eastern Mediterranean city (possibly Antioch) fixed Nisan 14 on March 11 in AD 328, on March 5 in AD 334, on March 2 in AD 337, and on March 10 in AD 339, all well before the spring equinox. This led some Christians to experiment with their own computations. However, others advised, “Do not do your own computations, but instead observe Passover when your brethren from the circumcision do. If they err, it is no matter to you....”

Painting of the Council of Nicea

THE COUNCIL OF NICAEA TACKLES THE ISSUE

Constantine addressed the issue when he convened the Council of Nicaea and severed any remaining tie between Christianity and Judaism when he wrote, “It appeared an unworthy thing that in the celebration of this most holy feast we should follow the practice of the Jews...For we have it in our power, if we abandon their custom, to prolong the due observance of this ordinance to future ages by a truer order...For their boast is absurd indeed, that it is not in our power without instruction from them to observe these things....Being altogether ignorant of the true adjustment of this question, they sometimes celebrate Passover twice in the same year.”

As a result, the First Council of Nicaea in 325 endorsed the idea of independent calculations and set the date of Easter as the Sunday following the paschal full moon, which is the full moon that falls on or after the vernal (spring) equinox.

Constatine the Great

A TALE OF TWO CALENDARS

The Church does not use the exact date of the paschal full moon but an approximation, because the paschal full moon can fall on different days in different time zones, which raises the old problem of having more than one date for Easter. For purposes of calculating the date of Easter, the full moon is assumed to be the 14th day of the lunar month. The Church also set the date of the vernal equinox as March 21, even though it sometimes occurs on March 20. Using these approximations allowed the Church to set a universal date for Easter. If only it were that simple. 

The world of Constantine ran on the Julian calendar. Introduced by Julius Caesar in 45 BC as a reform of the Roman calendar, it was developed with the help of astronomer Sosigenes of Alexandria. It contained 365 days a year and allowed for a leap year every fourth year. As accurate as it was, the Julian calendar was still off by 11 minutes a year. This tiny error caused it to gain three days every four centuries. The Gregorian calendar, introduced in 1582 and still in use today, eliminated this problem.  

But by that time the Church had split into an Eastern, or Orthodox, branch and a Western, or Roman, branch. The Western Church calculates Easter using the Gregorian calendar. Our Eastern brothers, however, seeking to celebrate the traditional date of the Pascha, continue to adhere to the older Julian calendar. Because of the Julian calendar’s continual slippage, March 21 on the Julian calendar corresponds to April 3 on the Gregorian calendar.  

Easter can come no earlier than March 22^nd. and no later than April 25^th. However, by the following the Julian calendar, the Orthodox celebration of Pascha can fall between April 4 and May 8. Some Orthodox communities have begun using a revised Julian calendar for their calculations and others retain the older ways.  

Since the full moon is at the root of both calculations, the date of Easter/Pascha depends upon which moon is chosen. In those years when both branches of the Church use the same moon, the date of the Feast is the same. When the Eastern Church uses a later moon, there can be an extreme variance.  For instance, both branches celebrated Easter on April 24^th in 2011. The date in 2012 for the Western Church is April 8^th while for the Eastern Church it will be April 15^th. For 2013, the dates are March 31^st in the West and May 5^th in the East. In 2014, the dates again converge on April 20^th. 

With an eye toward the crucifixion and burial of Jesus on Good Friday, next time we’ll look at ancient burial practices.  

Until then, we wish you Peace and Blessings.

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