Easter – Setting the Date

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Easter – Setting the Date

Easter Sunday is the date of the annual celebration of Christ’s resurrection. In the church calendar, Easter Sunday is the point of reference from which the entire church calendar year of movable events is calculated. Easter always occurs on the first Sunday after the first full moon after the vernal equinox. The date of Easter can be as early as March 22 or as late as April 25. The aim of the Easter Dating Method is to maintain, for each Easter Sunday, the same season of the year and the same relationship to the preceding astronomical full moon that occurred at the time of his resurrection in 30 A.D.

The date for Easter has not always been calculated in this way. In the first two centuries A.D., in Asia Minor, Christians celebrated Easter on the third day after the first full moon of spring. It was always the third day, regardless of the day of the week on which this occurred. This date was based on the Jewish Passover. The Jewish month consists of one lunar phase of 28 days beginning and ending with the full moon. The full moon, therefore, always occurs on the fourteenth of every month of the Jewish calendar. Passover is the fourteenth of the month of Nisan. Not all Quartodecimans chose to celebrate Easter on the same day, some celebrated Easter on Passover day, some three days after Passover. According to the Gospels the Last Supper took place on Passover Eve and the Resurrection three days later. For this reason Easter was celebrated independent of any particular weekday. The followers of this dating for Easter were known as the Quartodecimans (quartodecimus = 14, for 14th of Nissan).

Not all Christians celebrated Easter on the same day. From 31 A.D. to 325 A.D. Easter Day was celebrated either as the Quartodecimans did or on a Sunday close to Passover Day. Both of these methods existed continuously throughout this period. The Christian communities under Rome’s leadership always celebrated Easter on Sunday – the first day of the week. The largest group of churches churches that chose to celebrate Easter according to the Jewish calendar were those of Syria and Mesopotamia. They believed they had apostolic direction to celebrate Easter on the same day that the Jews celebrate Passover. The problem was that the Jewish calendar was constantly being revised and changed to make up for errors in calculation and misalignment with the seasons.

During the second century the differing date for the celebration of Easter resulted in the Easter Dispute. This dispute was not settled until until 325 A.D. by the Council of Nicea.The Council of Nicea, noting that Syria and Mesopotamia represented a small minority, required them to conform to the practice of the majority. The bishops from Syria and Mesopotamia agreed to this ruling and their churches complied with it. The Council of Nicea also ruled that all churches must celebrate Easter on the same day. Even though the dispute was supposedly settled, some Quartodecimans continued to celebrate Easter by their calculation until the fifth century. As a result of the agreements at Nicea, the Alexandrian Bishops were officially commissioned to announce the Sunday on which Easter should fall.

Due to the use of two different calendars the Easter Sundays of the Roman Church did not correspond to those of the Alexandrian Church. The Roman calendar was based on a cycle in which Easter fell on the same date every 84 years. With the Alexandrian calendar Easter Sunday fell on the same date every 19 years. The formula for the calculation of Easter became standard about the year 540. At this time Dionysius Exiguus introduced the Alexanderian calendar to Rome. This is the 19 year cycle that all Christian churches use to calculate the date for Easter today. The formula for the calculation of Easter is known as Nicene formula, although it cannot be proved that the Council of Nicea prescribed the mathematical formula that we presently use to fix the date of Easter.

Still another date for Easter?

“Wait a minute!” you say. Previously it was stated that the calculation for Easter is the same for all Christian churches today, and it is. Why then do the Orthodox churches generally celebrate Easter on a different Sunday?

From 326 A.D. to 1582 A.D. the Easter Sunday date was based on the Julian calendar in use at that time. The Julian calendar was replaced by the Gregorian calendar in October 1582 (in most countries) to re-align the calendar with the seasons. The Gregorian calendar very closely maintains the alignment of seasons and calendar dates, but it is a secular calendar.

The Western Church applies the Nicene formula to the calendar as reformed by Pope Gregory in 1582. The Eastern Church applies the Nicene formula to the old Julian Calendar, which was instituted by Julius Caesar and served as the civil calendar of the Roman Empire before the birth of Christ. The Eastern Church also applies the formula in such a way that Easter always falls after the Jewish Passover. Orthodox churches became fully autonomous in 1054 A.D., and celebrate their Easter always on the basis of the Julian calendar. Consequently, the Orthodox Easter Sunday dates are identical up to 1582, then from 1583 onwards often differ from those of Western churches.

In some years the Orthodox Easter Sunday occurs on the same day as the Western Easter Sunday. For example, this occurred in 1990 because the Western Easter Sunday date of (Gregorian calendar) April 15, 1990 is the same as the Orthodox Easter Sunday date of (Julian calendar) April 2, 1990. In most years, Orthodox Easter follows Western Easter by one or more weeks. The Orthodox churches use the same 19 year cycle and formula to calculate Easter’s date, but they do so with a different calendar.

Once you choose your calendar – either Julian or Gregorian – the calculation for the date of Easter is quite simple. It is the first Sunday after the first Full Moon, after the vernal equinox. The vernal equinox is either March 20 or 21. The full moon is always – Well that is difficult to figure out. Just stay up late each night an look to see when the moon is full. If you need to know ahead of time, that method is not too reliable. The moon cycle is 28 days and it gets complicated to relate that to a 28 to 31 day month.

Below is a formula and chart to calculate the date of Easter Day. This method is valid for any year, but only for the Western Church (Gregorian Calendar).

Take the number of the year, add one, then divide by 19 (Remember the 19 year cycle introduced by Dionysius Exiguus). Discard the answer and take the remainder. Match up the remainder with the table below. Easter is the first Sunday after the date in the table.

For example, 2009 plus 1 is 2010. If you divide 2010 by 19, the answer is 105 with a remainder of 15. The date in the table for 15 is April 10. Therefore, Easter Day falls on the following Sunday, which is April 12, 2009.

Let’s do next year: 2010 + 1 = 2011, divide by 19 = 105 with a remainder of 16. This is March 30 on the table. That means Easter is the 1st Sunday after that date which is April 4, 2010.

If all of this seems a bit much for you – you can always check the calendar. Slowly and quietly the Christian world moves toward adoption of a fixed date for Easter. Most likely choice: the first Sunday in April. Already, I remember reading that the Orthodox churches are in agreement to celebrate Easter on the same day as other Christian churches. I don’t know when this will take effect and I’ve lost documentation for this agreement.

Sources Include: The Dictionary of Bible and Religion, William Gentz | The Bible Almanac, White | Easter a Pictorial Pilgrimage – Pierre Benoit |

The Chart:

Remainder	Date	Remainder	Date
0	March 27	10	April 5
1	April 14	11	March 25
2	April 3	12	April 13
3	March 23	13	April 2
4	April 11	14	March 22
5	March 31	15	April 10
6	April 18	16	March 30
7	April 8	17	April 17
8	March 28	18	April 7
9	April 16	-	-

This was a very long blog – I think I’ll take Sunday off and return on Monday with a few quotations.