Revised Julian calendar
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The Revised Julian calendar is a calendar scheme, originated in 1923, which effectively discontinued the 340 years of divergence between the naming of dates sanctioned by those Eastern Orthodox churches adopting it and the Gregorian calendar scheme that has come to predominate worldwide. (After about eight centuries, the two schemes will diverge again, though more slowly than the Julian and Gregorian do.)
The term "Revised Julian" is informative primarily in describing the fact that it replaces the de facto Orthodox endorsement of the Julian scheme, and has the effect of avoiding any implicit recognition of Pope Gregory XIII's promulgation of a system with the same goals and general approach in the Gregorian reform of 1582. Despite its terminology and the application of improved scientific knowledge, it departs from the Julian calendar in essentially the same direction that the Gregorian did.
The Revised Julian scheme was proposed for adoption by the Orthodox churches at a synod in Istanbul in May 1923. The synod synchronized the new calendar with the Gregorian calendar by specifying that the next 1 October of the Julian calendar would be 14 October in the Revised Julian calendar, thus dropping thirteen days. It then adopted a leap year rule that differs from that of the Gregorian calendar: Years evenly divisible by four are leap years, except that years evenly divisible by 100 are not leap years, unless they leave a remainder of 200 or 600 when divided by 900, then they are leap years. This means that the two calendars will first differ in 2800, which will be a leap year in the Gregorian calendar, but a common year in the Revised Julian calendar. This leap year rule was proposed by Milutin Milanković, an astronomical delegate to the synod, representing the Kingdom of Serbs, Croats and Slovenes.
Milanković selected this rule, which produces an average year length of 365.242222… days, because it was within two seconds of the then current length of the mean tropical year. However, the vernal equinox year is slightly longer, so for a few thousand years the Revised Julian calendar doesn't do as good a job as the Gregorian calendar at keeping the vernal equinox on or close to March 21. But the length of a day is increasing by about 1.7 milliseconds per century (see tidal acceleration), so the number of days per year decreases by about 0.0001 each millennium. This means that in the long run, the Revised Julian calendar will also be inaccurate even if the mean tropical year is the basis.
The Revised Julian calendar was adopted by the Orthodox churches of Constantinople, Alexandria, Antioch, Greece, Cyprus, Romania, Poland, and Bulgaria (the last in 1963), called the New calendarists. It was rejected by the Orthodox churches of Jerusalem, Russia, Serbia, Georgia and the Greek Old Calendarists. Although Milanković stated that the Russian Orthodox Church adopted the Revised Julian calendar in 1923, the present church continues to use the Julian calendar for both its fixed festivals and for Easter. A solution to this conundrum is to hypothesize that it was accepted only by the short-lived schismatic Renovationist Church, which had seized church buildings with the support of the Soviet government while Patriarch Tikhon was under house arrest. After his release, on 15 July 1923, he declared that all Renovationist decrees were without grace, presumably including its acceptance of the Revised Julian calendar.
The synod also adopted an astronomical rule for Easter: Easter is the Sunday after the midnight-to-midnight day at the meridian of the Church of the Holy Sepulchre in Jerusalem (35°13'46"E or UT+2h20m55s for the large dome) during which the first full moon after the vernal equinox occurs. Although the instant of the full moon must occur after the instant of the vernal equinox, it may occur on the same day. If the full moon occurs on a Sunday, Easter is the following Sunday. However, all Eastern Orthodox churches rejected this rule and continue to use the Julian calendar to determine the date of Easter (except for the Finnish Orthodox Church, which now uses the Gregorian Easter).
[edit] Reference
- Miriam Nancy Shields, "The new calendar of the Eastern churches", Popular Astronomy 32 (1924) 407-411. This is a translation of M. Milankovitch, "The end of the Julian calendar and the new calendar of the Eastern churches", Astronomische Nachrichten No. 5279 (1924).
