Friday, March 07, 2008

Determining the Date of Easter


by Brother John M. Samaha, S.M.
reprinted with permission

People often puzzle over the different dates on which Easter is celebrated. The different dates are determined by the different calendars used for reckoning Easter.

Biblical Background
In the Old Testament, the Jews celebrated the feast of Passover, or Pasch, in remembrance of their deliverance from Egypt. The Book of Exodus, chapter 12, tells the story.

Thereafter the celebration of Passover was begun on the fourteenth day of Nisan (Abib), the Paschal full moon following the spring equinox (Leviticus 23:5-8; Deuteronomy 16:1-8). Spring equinox is when day and night are equal.

The Jewish calendar, however, since it was a lunar calendar consisting of twelve or thirteenth months per year, caused difficulties in determining the day of the spring equinox. Consequently, Passover celebrations would begin on the full moon of either March or April of the Julian calendar.

The Gospel of St. John explicitly states that the death of Jesus coincided with the Paschal celebrations of the Jewish people (John 13:1; 19:31).

Early Christian History
The Christians in Asia Minor, Caesarea, Syria, and Mesopotamia observed Easter on the first day of the Jewish Passover. But the Christians in Rome and Egypt celebrated Easter on the Sunday after the Jewish Passover.

Pope St. Anicetus (155-166) supported the celebration of Easter on the Sunday after the Jewish Pasch. Pope St. Victor (189-198) upheld this practice.

Controversy ensued, and Pope St. Sylvester I resolved the matter at the first ecumenical council at Nicaea, Asia Minor, in 325. The general council decreed that Easter be celebrated on the first Sunday following the Paschal full moon after the spring equinox.

The Julian Calendar
From that time for 1,247 years Easter was celebrated on the same Sunday in the entire Christian Church -- East and West. According to the Julian calendar, March 21 was considered the day of the spring equinox in the Roman Empire.

Eventually the inaccuracies of the Julian calendar witnessed Christians in the sixteenth century celebrating Easter on different Sundays.

In 46 B.C. Julius Caesar had originated the Julian calendar. The astronomers of his time calculated the solar year to have 365 days and six hours. Every fourth year became a leap year with 366 days. This was remarkably close, but each year was too long by 11 minutes and 14 seconds. This small difference accumulated to one day in 128 years. In addition the astronomers figured that the moon cycle of 19 years was exact, that is, that the full moon returned to the identical day and hour after 19 years. However, the cycle was too long by one hour and 29 minutes. This difference amounted to one day in 308 years. By the sixteenth century astronomers were alarmed that the Julian calendar was out of congruence with the seasons of the years by ten days, and with the cycles of the moon by four days.

The Gregorian Calendar
In 1582 Pope Gregory XIII asked the leading astronomers to correct these inaccuracies, and he proclaimed some changes in the Julian calendar. Regarding the solar year ten days were dropped from the calendar, and that year October 5 became October 15. In the future three leap years would be omitted every 400 years. To rectify the moon cycle the calendar full moon was drawn back four days. In the future the calendar full moons were to be drawn back one day eight times in 25 centuries. With these reforms the Julian calendar was brought very close to the astronomical solar year and the astronomical moon cycle.

The Gregorian calendar took its name from Pope Gregory XIII, who proclaimed it to the world.

The Catholic countries of Europe quickly accepted the new Gregorian calendar: Italy, France, Poland, Spain, and Portugal. The Protestant countries—Germany, England (including North America), Denmark, Sweden, Norway—adopted it about 200 years later. The non-Christian countries of Japan, China, Siam (Thailand), Turkey, Egypt, etc., accepted it about 350 years later. The Orthodox countries—Greece, Bulgaria, Russia, Ukraine, and the patriarchates of Constantinople, Antioch, and Alexandria—adopted it in the twentieth century in civil and historic matters only. They still observe religious feasts (Christmas, Easter, Pentecost, etc.) according to the Julian calendar. This divergence can place the celebrations of Easter as much as five weeks apart.

In determining the date of Easter the discrepancy between the Julian and Gregorian calendars grows each year.

Easter is early this year, 2008. Actually it can be one day earlier, March 22; but that rarely happens. This year is the earliest Easter we will experience in our lifetime.

The next time Easter will be this early, March 23, will be in 2228. The last time it was this early was 1913.

The next time Easter falls a day earlier, March 22, will be in 2285. The last time it was celebrated on March 22 was in 1818.

But what is really important is that Christ is risen. He is truly risen.

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