20th-Century Proposals for the Astronomical Calculation of Easter

Introduction

When Pope Gregory XIII issued the papal bull Inter gravissimas on 25 February 1582, in which he urged all Christians to adopt the reformed calendar and the improved Easter reckoning, he also hoped that the Orthodox Christians would accept it. However, despite the efforts of the emissaries of the Pope to convince the Orthodox Church to accept the new calendar, it was rejected by the Orthodox Church. The main reason for its rejection was that the celebration of Easter would be altered: contrary to the injunctions of canon 7 of the Holy Apostles, the decree of the First Ecumenical Synod (Nicaea, 325), and canon 1 of Ancyra, Easter would sometimes coincide with the Jewish Passover in the Gregorian calendar.

The “Pan-Orthodox Congress” of 1923

In May of 1923, however, an “Inter-Orthodox Congress” was convened at Constantinople by the then Ecumenical Patriarch, Meletios IV. Not all Orthodox Churches were in attendance. The Churches of Serbia, Romania, Greece, and Cyprus were; the Churches of Alexandria, Antioch and Jerusalem, although invited, were not; the Church of Bulgaria was not invited. Several issues were under discussion at the congress, one of which was the adoption of the New Calendar. No unanimous agreement was reached on any of the issues discussed.

In May 1923 the so-called “Pan-Orthodox Congress” of the orthodox Christian Churches was held in Istanbul (Constantinople) that was chaired by the patriarch Meletius IV.

Milutin Milankovitch (1879-1958), a Serbian scientist who is now best remembered for his astronomical studies on the Ice Ages.

It was adopted by Pan Orthodox Congress, not by Greek Orthodox Church. Congress was held in Constantinople in 1923. Ecumenical Patriarchate organized the Congress, and Serbian and Rumanian Orthodox Churches participated, and Ecumenical Patriarchate. There was one delegation which pretended to represent Russian Orthodox Church, but in fact it did not - the confusion arose due to the the difficult situation in Russia following the Bolsjevik revolution.

The Greek Orthodox Church, in Athens, adopted Gregorian calendar in 1924, as well as in Rumanian. But they did not adopt the Gregorian epacts – Easter is calculated according to the Julian epacts. Do not mix Ecumenical Patriarchate with Greek Orthodox Church, it is not the same. All Churches which took part in Constantinople are independent.

One of the points discussed during this congress was the revision of the Julian calendar and the calculation of Easter and the other movable feast days.

The Reformed Orthodox Calendar

At the conclusion of the congress, the following resolutions were issued:

1. The Julian calendar would corrected by deleting the 13 days that it had advanced on the seasons since the first oecumenical council of Nicaea in AD 325. The correction would be implemented by skipping the first 13 days of October in that year, so that Saturday 30 September would be followed by Sunday 14 October.
2. The religious celebrations that would have been held on the omitted days would all be observed on 14 October or at a later time as ordained by the “Bischof des Kirchensprengels”.
3. All months would keep the same number of days as they had previously. In leap years the month of February would contain 29 days.
4. As before there would be two kinds of years: common years of 365 days and leap years of 366 days. With the exception of centennial years (see resolution 5), leap years would be those years which were evenly divisible by four.
5. The centennial years ???. In the following scheme the centennial leap years are given in bold:
    
   2000  2100  2200  2300  2400  2500  2600  2700  2800
   2900  3000  3100  3200  3300  3400  3500  3600  3700
   3800  3900  4000  4100  4200  4300  4400  4500  4600
   etc.
    
6. The fixed feast days (such as Christmas) would be observed on the same days as before.
7. The movable feast days will be regulated by Easter day. According to the canonical rules, that will be remain unchanged, Easter will be observed on the Sunday following the day of the first (astronomical) Full Moon after the (astronomical) Spring Equinox.
8. The Easter calculations will be performed according to the most reliable theories of the motions of the Sun and the Moon, adopting the meridian of the holy city of Jerusalem as reference meridian.
9. Help will be enlisted from astronomers at the observatories of Athens, Belgrado, Bucharest and Pulkowo to calculate accurate and extensive Easter tables for distribution within the orthodox church communities.
10. The present reform is only temporary and should not impede any future calendar reforms.

With the modified leap year rule, the Reformed Orthodox Calendar is even more accurate than the Gregorian Reform. As 900 years contain (9 × 25) – 7  = 218 leap days, the average length of the calendar year is 365 ²¹⁸/900 = 365.242222.... days or exactly 365 days 5 hours 48 minutes 48 seconds.

Aleppo 1997 Proposal for the Astronomical Calculation of Easter

In March 1997 delegates from the World Council of Churches and the Middle East Council of Churches convened in Aleppo (Syria) to discuss the problem of the current Western and Orthodox calculations.

??? in favour of astronomical prediction: the Sunday following the Jerusalem meridian day of the first astronomical Full Moon after the astronomical March Equinox. Jerusalem meridian time is 2 hours and 21 minutes ahead of Greenwich. Read more about this in the World Council of Churches article that is the source of this information.

Table of Astronomical Easters from 1900 to 2200

The following table lists all cases between 1900 and 2200 when the date of astronomical Easter Sunday differs from that calculated by the Gregorian Easter rules. The times for the spring equinox and the astronomical Full Moon are based on the meridian of Jerusalem, which was adopted to be 35º 13' (2h 20.9m) East of Greenwich.

Occasionally, the date of astronomical Easter Sunday will fall outside the traditional Easter Sunday limits (22 March to 25 April) and can occur on dates such as 21 March (not until in 2877) and 26 April (in 1829, 1981, 2201, 2353, 2725, etc.).