Revised Julian calendar

The Revised Julian calendar or Meletian Calendar or, less formally, New 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.

History

The Revised Julian scheme was proposed for adoption by the Orthodox churches at a synod in Constantinople in May 1923. The synod synchronized the new calendar with the Gregorian calendar by specifying that the next October 1 of the Julian calendar would be October 14 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. The alternative name, Meletian Calendar, comes from his latinized name.

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 does not 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 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+2^h20^m55^s 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).

Arithmetic

The following are Gregorian minus Revised Julian date differences, calculated for the beginning of March in each century year, which is where differences arise or disappear, until 10000 AD. These are exact arithmetic calculations, not depending on any astronomy. A negative difference means that the proleptic Revised Julian calendar was behind the proleptic Gregorian calendar. The Revised Julian calendar is the same as the Gregorian calendar from 1 March 1600 to 28 February 2800. A positive difference means that the Revised Julian calendar will be ahead of the Gregorian calendar, which will first occur on 1 March 2800:

Gregorian minus Revised Julian date differences

Century Difference	100 0	200 −1	300 −1	400 0	500 0	600 −1	700 −1	800 0	900 0	1000 0
Century Difference	1100 −1	1200 0	1300 0	1400 0	1500 −1	1600 0	1700 0	1800 0	1900 0	2000 0
Century Difference	2100 0	2200 0	2300 0	2400 0	2500 0	2600 0	2700 0	2800 +1	2900 0	3000 0
Century Difference	3100 0	3200 +1	3300 0	3400 0	3500 0	3600 +1	3700 +1	3800 0	3900 0	4000 +1
Century Difference	4100 +1	4200 0	4300 0	4400 +1	4500 +1	4600 +1	4700 0	4800 +1	4900 +1	5000 +1
Century Difference	5100 0	5200 +1	5300 +1	5400 +1	5500 +1	5600 +1	5700 +1	5800 +1	5900 +1	6000 +1
Century Difference	6100 +1	6200 +1	6300 +1	6400 +2	6500 +1	6600 +1	6700 +1	6800 +2	6900 +1	7000 +1
Century Difference	7100 +1	7200 +2	7300 +2	7400 +1	7500 +1	7600 +2	7700 +2	7800 +1	7900 +1	8000 +2
Century Difference	8100 +2	8200 +2	8300 +1	8400 +2	8500 +2	8600 +2	8700 +1	8800 +2	8900 +2	9000 +2
Century Difference	9100 +2	9200 +2	9300 +2	9400 +2	9500 +2	9600 +2	9700 +2	9800 +2	9900 +2	10000 +3

In 900 Julian years there are ⁹⁰⁰⁄₄ = 225 leap days. The Revised Julian leap rule omits seven of nine century leap years, leaving 225−7 = 218 leap days per 900-year cycle. Thus the calendar mean year is 365+²¹⁸⁄₉₀₀ days, but this is actually a double-cycle that reduces to 365+¹⁰⁹⁄₄₅₀ = 365.24(2) days, or exactly 365 days 5 hours 48 minutes 48 seconds, which is exactly 24 seconds shorter than the Gregorian mean year of 365.2425 days, so in the long term on average the Revised Julian calendar pulls ahead of the Gregorian calendar by one day in 3600 years.

The number of days per Revised Julian cycle = 900 × 365 + 218 = 328,718 days. Taking mod 7 leaves a remainder of 5, so like the Julian calendar, but unlike the Gregorian calendar, the Revised Julian calendar cycle does not contain a whole number of weeks. Therefore, a full repetition of the Revised Julian leap cycle with respect to the seven-day weekly cycle is seven times the cycle length = 7 × 900 = 6300 years.

Adoption

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 July 15, 1923, he declared that all Renovationist decrees were without grace, presumably including its acceptance of the Revised Julian calendar.

Criticism

While the Revised Julian calendar has been adopted by many of the smaller national churches, a majority of Orthodox Christians continue to adhere to the traditional Julian Calendar, and there has been much acrimony between the two parties over the decades since the change, leading sometimes even to violence, especially in Greece. Criticism of the calendar tends to fall into two categories: social and liturgical.

Critics see the change in calendar as an unwarranted innovation, influenced by Western society. They say that no sound theological reason has been given for changing the calendar, that the only reasons advanced are social. The argument is also made that since the use of the Julian Calendar was implicit in the decision of the First Ecumenical Council at Nicea (325) which fixed the date of Pascha (Easter), no authority less than an Ecumenical Council may change it. The adoption of a new calendar has broken the unity of the church, undoing the whole purpose of the council of Nicea, so once again, "some on the same day some should be fasting whilst others are seated at a banquet."

Liturgical objections to the New Calendar stem from the fact that it adjusts only those liturgical celebrations that occur on fixed calendar dates, leaving all of the commemorations on the moveable cycle on the original Julian Calendar. This upsets the harmony and balance of the liturgical year. This disruption is most noticeable during Great Lent. Certain feast days are designed to fall during Lent, such as the feast of the Forty Martyrs of Sebaste. The Feast of the Annunciation is also intended to fall either before Pascha or during Bright Week. Sometimes, Annunciation will fall on the day of Pascha itself, a very special concurrence known as Kyrio-Pascha, with special liturgical practices appointed for such an occurrence. However, under the Revised Julian calendar, Kyrio-Pascha becomes an impossibility. The Apostles' Fast displays the most difficult aspect of the Revised Julian calendar. The fast begins on the moveable cycle and ends on the fixed date of June 29; since the Revised Julian calendar is 13 days ahead of the traditional Julian calendar, the Apostles' Fast is 13 days shorter for those who follow the New Calendar, and some years it is completely abrogated. Furthermore, critics of the New Calendar point out the definite advantage to celebrating Nativity separately from the secular observance of Christmas.

Calculation

The EDP is for Weekday determination often the Doomsday algorithm used. Another possibility is described in the following definition of the Dominical letter.

(For leap years are valid for two Sunday letters, the left for January and February, the right for the rest of the year.)

Orthodox Calendar					The first digits of the year
					19	20		21		22
					23	24		25		26
					27		28	29		30
					31		32	33		34
these secular years					35		36		37	38
Leap years are					39		40		41	42
					43		44		45		46
					47		48		49		50
					51		52		53		54
						55	56		57		58
Orthodox Calendar						59	60		61		62
repeats						63		64	65		66
after 6300 years:						67		68	69		70
						71		72		73	74
8200 is like 1900						75		76		77	78
						79		80		81
Years
	20	48	76		DC	ED	FE	GF	AG	BA	CB
	21	49	77		B	C	D	E	F	G	A
	22	50	78		A	B	C	D	E	F	G
00	23	51	79		G	A	B	C	D	E	F
	24	52	80		FE	GF	AG	BA	CB	DC	ED
	25	53	81		D	E	F	G	A	B	C
	26	54	82		C	D	E	F	G	A	B
	27	55	83		B	C	D	E	F	G	A
00	28	56	84		AG	BA	CB	DC	ED	FE	GF
01	29	57	85		F	G	A	B	C	D	E
02	30	58	86		E	F	G	A	B	C	D
03	31	59	87		D	E	F	G	A	B	C
04	32	60	88		CB	DC	ED	FE	GF	AG	BA
05	33	61	89		A	B	C	D	E	F	G
06	34	62	90		G	A	B	C	D	E	F
07	35	63	91		F	G	A	B	C	D	E
08	36	64	92		ED	FE	GF	AG	BA	CB	DC
09	37	65	93		C	D	E	F	G	A	B
10	38	66	94		B	C	D	E	F	G	A
11	39	67	95		A	B	C	D	E	F	G
12	40	68	96		GF	AG	BA	CB	DC	ED	FE
13	41	69	97		E	F	G	A	B	C	D
14	42	70	98		D	E	F	G	A	B	C
15	43	71	99		C	D	E	F	G	A	B
16	44	72			BA	CB	DC	ED	FE	GF	AG
17	45	73			G	A	B	C	D	E	F
18	46	74			F	G	A	B	C	D	E
19	47	75			E	F	G	A	B	C	D

Determination of the weekday with the Sunday letters

A	B	C	D	E	F	G		January					February					March					April
Sun	Sat	Fri	Thu	Wed	Tues	Mon		1	8	15	22	29		5	12	19	26		5	12	19	26		2	9	16	23	30
Mon	Sun	Sat	Fri	Thu	Wed	Tues		2	9	16	23	30		6	13	20	27		6	13	20	27		3	10	17	24
Tues	Mon	Sun	Sat	Fri	Thu	Wed		3	10	17	24	31		7	14	21	28		7	14	21	28		4	11	18	25
Wed	Tues	Mon	Sun	Sat	Fri	Thu		4	11	18	25		1	8	15	22	29	1	8	15	22	29		5	12	19	26
Thu	Wed	Tues	Mon	Sun	Sat	Fri		5	12	19	26		2	9	16	23		2	9	16	23	30		6	13	20	27
Fri	Thu	Wed	Tues	Mon	Sun	Sat		6	13	20	27		3	10	17	24		3	10	17	24	31		7	14	21	28
Sat	Fri	Thu	Wed	Tues	Mon	Sun		7	14	21	28		4	11	18	25		4	11	18	25		1	8	15	22	29
A	B	C	D	E	F	G		May					June					July						August
Sun	Sat	Fri	Thu	Wed	Tues	Mon			7	14	21	28		4	11	18	25		2	9	16	23	30		6	13	20	27
Mon	Sun	Sat	Fri	Thu	Wed	Tues		1	8	15	22	29		5	12	19	26		3	10	17	24	31		7	14	21	28
Tues	Mon	Sun	Sat	Fri	Thu	Wed		2	9	16	23	30		6	13	20	27		4	11	18	25		1	8	15	22	29
Wed	Tues	Mon	Sun	Sat	Fri	Thu		3	10	17	24	31		7	14	21	28		5	12	19	26		2	9	16	23	30
Thu	Wed	Tues	Mon	Sun	Sat	Fri		4	11	18	25		1	8	15	22	29		6	13	20	27		3	10	17	24	31
Fri	Thu	Wed	Tues	Mon	Sun	Sat		5	12	19	26		2	9	16	23	30		7	14	21	28		4	11	18	25
Sat	Fri	Thu	Wed	Tues	Mon	Sun		6	13	20	27		3	10	17	24		1	8	15	22	29		5	12	19	26
A	B	C	D	E	F	G		September					October					November					December
Sun	Sat	Fri	Thu	Wed	Tues	Mon			3	10	17	24	1	8	15	22	29		5	12	19	26		3	10	17	24	31
Mon	Sun	Sat	Fri	Thu	Wed	Tues			4	11	18	25	2	9	16	23	30		6	13	20	27		4	11	18	25
Tues	Mon	Sun	Sat	Fri	Thu	Wed			5	12	19	26	3	10	17	24	31		7	14	21	28		5	12	19	26
Wed	Tues	Mon	Sun	Sat	Fri	Thu			6	13	20	27	4	11	18	25		1	8	15	22	29		6	13	20	27
Thu	Wed	Tues	Mon	Sun	Sat	Fri			7	14	21	28	5	12	19	26		2	9	16	23	30		7	14	21	28
Fri	Thu	Wed	Tues	Mon	Sun	Sat		1	8	15	22	29	6	13	20	27		3	10	17	24		1	8	15	22	29
Sat	Fri	Thu	Wed	Tues	Mon	Sun		2	9	16	23	30	7	14	21	28		4	11	18	25		2	9	16	23	30

To calculate a day of week given the date see Zeller's congruence and Calculating the day of the week.

External links

• Liturgical Havoc Wreaked by the "New Julian" Calendar by Hieromonk Cassian
• The Essence of the Church Calendar