Coptic calendar

From Academic Kids

The Coptic calendar, also called the Alexandrian Calendar, is used by the Coptic Orthodox Church. It is based on the Ancient Egyptian calendar. To avoid the calendar creep of the latter, a reform of the Ancient Egyptian calendar was introduced at the time of Ptolemy III (Decree of Canopus, in 238 BC) which consisted in the intercalation of a 6th epagomenal day every fourth year. However, this reform was opposed by the Egyptian priests, and the idea was not adopted until 25 BC, when the Roman Emperor Augustus formally reformed the calendar of Egypt, keeping it forever synchronized with the newly introduced Julian calendar. To distinguish it from the Ancient Egyptian calendar, which remained in use by some astronomers until medieval times, this reformed calendar is known as the Coptic calendar.


The Coptic Year

The Coptic Year is the extension of the ancient Egyptian civil year, retaining its subdivision into the three seasons, four months each. The three seasons are commemorated by special prayers in the Coptic Liturgy. This calendar is still in use all over Egypt by farmers to keep track of the various agricultural seasons. The Coptic calendar has 13 months, 12 of 30 days each and an intercalary month at the end of the year of 5 or 6 days, depending whether the year is a leap year or not. The year starts on 11 September in the Gregorian Calendar or on the 12th in the year before (Gregorian) Leap Years. The Coptic Leap Year follows the same rules as the Gregorian so that the extra month always has six days in the year before a Gregorian Leap Year.

The Feast of Neyrouz marks the first day of the Coptic year. Its celebration falls on the 1st day of the month of Thout, the first month of the Coptic year, which usually coincides with 11 September, except before a Gregorian leap year when it's September 12. Coptic years are counted from AD 284, the year Diocletian became Roman Emperor, whose reign was marked by tortures and mass executions of Christians, especially in Egypt. Hence, the Coptic year is identified by the abbreviation A.M. (for Anno Martyrum or "Year of the Martyrs"). The A.M. abbreviation is also used for the unrelated Jewish year (Anno Mundi).

Every fourth Coptic year is a leap year without exception, like in the Julian calendar, so the above mentioned new year dates apply only between AD 1900 and 2099 inclusive in the Gregorian Calendar. In the Julian Calendar, the new year is always 29 August, except before a Julian leap year when it's August 30. Easter is reckoned by the Julian Calendar in the Old Calendarist way.

To obtain the Coptic year number, subtract from the Julian year number either 283 (before the Julian new year) or 284 (after it).

The Date of Christmas

The choice of 25 December to celebrate the Nativity of Christ was first proposed by Hippolytus of Rome (170–236), but was apparently not accepted until either 336 or 364. Dionysius of Alexandria emphatically quoted mystical justifications for this very choice:

March 25 was considered to be the anniversary of Creation itself. It was the first day of the year in the medieval Julian calendar and the nominal vernal equinox (it had been the actual equinox at the time when the Julian calendar was originally designed). Considering that Christ was conceived at that date turned March 25 into the Feast of the Annunciation which had to be followed, nine months later, by the celebration of the birth of Christ, Christmas, on December 25.

There may have been more practical considerations for choosing 25 December. The choice would help substitute a major Christian holiday for the popular pagan celebrations around the winter solstice (Roman Saturnalia or Brumalia). The religious competition was fierce. In 274, Emperor Aurelian had declared a civil holiday on December 25 (the Festival of the birth of the Unconquered Sun, or Sol Invictus) to celebrate the birth of Mithras, the Persian Sun-God whose cult predated Zoroastrianism and was then very popular among the Roman military. Finally, joyous festivals are needed at that time of year, to fight the natural gloom of the season. Whatever the actual reasons were for choosing a December 25 celebration, the scriptures indicate that the birth of Jesus of Nazareth did not even take place around that time of year, since there were in the same country sherperds living out in the fields, keeping watch over their flock by night (Luke 2:8). During cold months, shepherds brought their flocks into corrals and did not sleep in the fields. That's about all we know directly from scriptures, besides wild speculations.

Until the 16th century, 25 December coincided with 29 Koiak of the Coptic calendar. However, upon the introduction of the Gregorian calendar in 1582, December 25 shifted two weeks earlier in comparison with the Julian and Coptic calendars. This is the reason why Old-Calendrists (using the Julian and Coptic calendars) celebrate Christmas on January 7, two weeks after the New-Calendrists (using the Gregorian calendar), who celebrate Christmas on December 25.

The Date of Easter

According to Christian tradition, Jesus died at the ninth hour (that is, the canonical hour of nona or 'noon' in Middle English - 3:00 pm) of the first full day of Pesach, when that day fell on a Friday; and arose from the dead at or by the first (canonical) hour of that Sunday. The day of Pesach (Pascha or Passover, Nisan 15), is always at the first or second full moon following the vernal equinox. At the First Ecumenical Council, held in 325 at Nicaea, it was decided to celebrate Easter on the Sunday following the so-called Paschal full moon. The Paschal full moon is an arithmetical approximation to the first full moon after the vernal equinox. It may be expressed as follows in terms of the so-called Golden number (G) and Century term (C):

Except in two cases where the PFM is one day earlier than this, namely:

  • When (C+11G) is 0 modulo 30, PFM = 18 April (not 19 April).
  • When (C+11G) is 1 modulo 30, and G=12, PFM = 17 April (not 18).

The Golden number (G) is the same for both Julian and Gregorian computations, but the Century term is constant (C = +3) in Julian computations:

  • G = 1 + (Y mod 19) in year Y (Julian or Gregorian).
  • C = -H + H/4 + 8(H+11)/25 with H = Y/100 (Gregorian year Y)

C is -4 from 1583 to 1699, -5 from 1700 to 1899, -6 from 1900 to 2199, -7 from 2200 to 2299 etc... As the Sunday following the PFM, Easter is one week after the PFM when the PFM happens to fall on a Sunday. One must work with the Julian calendar (C = +3) to find when Easter is celebrated by Orthodox churches.

At the Council of Nicaea, it became one duty of the bishop of Alexandria to determine the exact dates of Easter and to announce it to the rest of the Christian churches. This duty fell on this officate because of the erudition at Alexandria he could draw on. The precise rules to determine this are very involved, but Easter is usually the first Sunday after a full moon occurring no sooner than March 21, which was the actual date of the vernal equinox at the time of the First Council of Nicaea. Shortly before Julius Caesar reformed the calendar, the vernal equinox was occurring on the "nominal" date of March 25. This was abandoned at Nicaea, but the reason for the observed discrepancy was all but ignored (the actual tropical year is not quite equal to the Julian year of 365 days, so the date of the equinox keeps creeping back in the Julian calendar).

See also: Computus

Coptic Months

Sources and external links

fr:Calendrier copte pl:Kalendarz koptyjski


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