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On the Christian Life

On the Question of the "Revised Julian Calendar"

The following article was originally posted to a mailing list in 1996. Later, it was published on the website of St. John the Baptist Cathedral in Washington, DC, and cited by other websites, including Wikipedia. When St. John's revamped their website in 2016, the article became unavailable. We republish it here, for archival purposes, which seems appropriate, since the author is now rector of this church. —Editor


The matter of the "Revised Julian Calendar" has recently been raised on this list and has generated some discussion. Since some were wondering about its relation to the traditional calendar of the Church, the Julian Calendar, on the one hand, and the Gregorian Calendar on the other, as well as the question of their astronomical accuracy, I thought the following might be helpful:

As everyone knows, the year is about 365 and a quarter days long. This is, however, only an approximation. We are concerned here with the seasonal, or tropical year, the average time from vernal equinox (the beginning of spring) to vernal equinox. The more accurate figure is 365.2422 days, a figure close to that known to the ancient Greek astronomers (Callippus, Ptolemy, et al). The Julian Calendar, the Church's traditional calendar, has 365 days in a year and an extra day added once every fourth year to February, making an average year length of 365.25 days. When the Church chose this as her own calendar at the Council of Nicaea (AD 325), the vernal equinox fell on 21 March. But since the Julian year is 0.0078 days longer than the true year, over a span of time 21 March will occur later than the astronomical equinox at the rate of about one day in 128 years.

By 1582, when Pope Gregory XIII changed the calendar, 21 March fell 10 days after the astronomical event. He adjusted the calendar by omitting 10 days from that year, so that the following year the astronomical equinox would fall on 21 March again, and he also adjusted the rule for leap years to keep the calendar date from drifting away from the astronomical event. This is accomplished by dropping a leap day every centennial year (those divisible by 100), but retaining the leap day every year divisible by 400. In other words, the years 1700, 1800, and 1900 are not leap years in the Gregorian calendar, but the years 1600 and 2000 are leap years. To obtain the average length of the Gregorian year, we must subtract from the Julian year three days in four hundred years,

365.25 - 3/400 = 365.25 - 0.0075 = 365.2425

The Gregorian year is therefore 365.2425 days, or 0.0003 day longer than the true tropical year. This error will accumulate to about one day every 3200 years. At a council held in Constantinople, attended mainly by representatives of the Patriarchate of Constantinopole under Patriarch Meletios Metaxakis, some astronomers proposed the "Revised Julian Calendar". Under this proposal, the Julian calendar would be corrected by dropping 13 days from the current year to bring the calendar 21 March in line with the astronomical equinox, and to keep it from drifting away from that date by omitting seven leap days every 900 years. That is to say, every centennial year would be a regular year without a leap day, except if when divided by 900 it leaves a remainder of 200 or 600. In other words, the years 1800, 1900, 2100, 2200, and 2300 would not be leap years but regular years because when divided by 900 they leave a remainder of 0, 100, 300, 400, and 500 respectively. But the years 2000 and 2400 would be leap years since these leave a remainder of 200 and 600 respectively when divided by 900. The average length of the calendar year is then, 365.25 days less 7 days in 900 years or

365.25 - 7/900 = 365.25 - 0.0077777... = 365.242222...

Which is almost exactly the length of the tropical year. This revision would make the calendar accurate to a day in about 40,000 years. This is the 900-year cycle that was mentioned by some on this list.

The differences between the three calendars can be summarized in the following table. The first column shows century years. The next heading under Leap Years shows which of the three calendars has that year as a leap year. J stands for the traditional Julian calendar, in which every year divisible by four is a leap year (including all century years), G stands for the Gregorian calendar, in which only the century years divisible by 400 are leap years, and R stands for the "Revised Julian Calendar" in which only those century years that leave a remainder of 200 or 600 when divided by 900 are leap years. The next column gives the difference between the Julian and Gregorian calendars in days. This difference holds for that century year and the 99 years that follow. The next column shows the difference between the traditional Julian Calendar and the "Revised Julian Calendar". The asterisks in the Gregorian and Revised columns are those century years that are leap years and the difference from the Julian calendar remains the same as the previous century.

Cent YearsLeap YearsGregorian vs Julian
G-J
Revised vs Julian
R-J
Gregorian vs Revised
R-G
100 J -1 -1 0
200 J R 0 -1* -1
300 J 1 0 -1
400 JG 1* 1 0
500 J 2 2 0
600 J R 3 2* -1
700 J 4 3 -1
800 JG 4* 4 0
900 J 5 5 0
1000 J 6 6 0
1100 J R 7 6* -1
1200 JG 7* 7 0
1300 J 8 8 0
1400 J 9 9 0
1500 J R 10 9* -1
1600 JG 10* 10 0
1700 J 11 11 0
1800 J 12 12 0
1900 J 13 13 0
2000 JGR 13* 13* 0
2100 J 14 14 0
2200 J 15 15 0
2300 J 16 16 0
2400 JGR 16* 16* 0
2500 J 17 17 0
2600 J 18 18 0
2700 J 19 19 0
2800 JG 19* 20 1
2900 J R 20 20* 0
3000 J 21 21 0
3100 J 22 22 0
3200 JG 22* 23 1
3300 J R 23 23* 0
3400 J 24 24 0
3500 J 25 25 0
3600 JG 25* 26 1

It is interesting that from the year 1600 to the year 2799, a span of 1200 years, the Gregorian and "Revised Julian" calendars agree exactly. From 2800 to 2899 they differ by one day, after which they again agree for another three hundred years. One may wonder whether for ecclesiastical purposes the adherents of the "Revised" calendar will celebrate their Holy Days one day earlier than the rest of the world for one century, or whether after so many centuries of agreement, they might not tacitly leave the matter as it had been.

Some adherents of the New Calendar claim that they have adopted a "Revised Julian Calendar", rather than the Papal Gregorian Calendar, and therefore they do not come under any penalty of the bans on that calendar adopted by the Pan Orthodox Councils of 1582 and 1583. However, for centuries to come, there is no practical difference between the Gregorian and "Revised Julian" calendars. They amount to the same thing. The payoff in astronomical accuracy will not be realized for several thousand years, far beyond any practical human purpose. One may wonder why one should devise a revision that is practically the same as that used by most of the world, and yet diverges in the distant future. For the next 800 years we would follow identical calendars, then by the time they diverge, the matter will have been settled one way or the other, and everyone would then remain on the same calendar. It is not too hard to guess which way will win.

It is also misleading to call this calendar the "Revised Julian", since the Gregorian Calendar itself is a revised Julian calendar.

I should like to touch on another subject mentioned on this list: the "leap second", a feature of scientific chronometry. Until recently the second was defined as 1/864,000 of a mean solar day (24 hours x 60 minutes per hour x 60 seconds per minute yield 864,000 seconds in a day). The earth, however, has slight seasonal variations in the rate of rotation (imperceptible except by the most sensitive instruments), and because a time standard was needed accurate to a fraction of an atomic vibration for global positional calculations, the national and international scientific chronometric standard has come to be the atomic clock. The second is now defined as a certain number of vibrations of a certain kind of atom, a rate determined by the laws of physics and presumably invariable. The earth, on the other hand is slowly running down, and the mean day is getting longer at the rate of about a millisecond per century. The difference between the actual length of the day and the nominal length defined as 864,000 seconds accumulates. After a number of years the mean astronomical midnight and midnight by the atomic clocks can diverge by as much as a second. At that point, by international agreement, everyone counts an extra second before midnight of New Year's day to bring the two standards once more into synchronization. This is the leap second. It does not follow a regular cycle, because it is determined by observation, and the differences accumulate irregularly. It has no practical effect on our daily lives.

In the long run, however, the slowing of the earth's rotation causes the number of days in the year to change very gradually. One effect of this is that no calendar that is cyclic can ever be more accurate than a day in about forty or fifty thousand years.

So far, I have only discussed the solar calendar. The Church determines Pascha and the feasts dependend upon it by taking into account a lunar reckoning. The Nicene Council adopted the lunar reckoning used by the Alexandrine astronomers, a 19-year cycle in which the phases of the moon repeat on the same calendar days. This, too, is an approximation, but it had the advantage of simplicity. After a long drawn out struggle the whole Church came to accept the Alexandrine Paschalion adopted by the Fathers of the First Ecumenical Council. Over the course of time, its use became deeply embedded within the festal cycle of the Church and provisions were made in the Typicon for all possible combinations of the lunar and solar reckoning. This recurred exactly every 532 years, over which the same pattern of Pascha dates were repeated. This is the product of the 19-year lunar cycle and the 28-year Sunday cycle (the days of the week repeat exactly in the Julian calendar every 28 years, this is the 4-year leap year cycle times the 7 possible days of the week), so that 19 x 28 = 532.

Since this lunar reckoning was also only approximate, and the error accumulated at the rate of one day in about 307 years, Pope Gregory also revised the lunar reckoning by dropping a day every 300 years. However the Gregorian Calendar is now practically not cyclic, since the period over which the calendar repeats is several thousand years.

The astronomers who proposed the "Revised Julian Calendar" offered no cyclic correction to the Alexandrine Paschalion, but proposed that the actual astronomical full moon after the astronomical vernal equinox, both calculated for the meridian of Jerusalem, be used to reckon the date of Pascha. This would have the effect of abolishing the periodicity of the calendar entirely. It would also make dating the festal calendar in the past and in the future extremely difficult, and would require complicated astronomical calculation. In the event, this proposal was not adopted by anyone, and the adherents of the "Revised Julian Calendar" had to be content with calculating the fixed feasts (the menolgy) by a calendar practically identical with the Papal calendar, and the movable feasts (Paschalion) according to the traditional Alexandrine (Julian) Paschalion, with all the dislocations that this entails. The Roman Church, and any Eastern Rite Catholics that follow the Papal Calendar, would never have any problem with circumstances unforeseen by the Typicon, since they would follow a consistent calendar that keeps Pascha between the conventional bounds of calendar 22 March and calendar 25 April. The calculation of the date of Gregorian Easter is not very simple.

The Traditional Paschalion, in contrast, is a model of simplicity. It has a 19-year table of Paschal full moons ("nomikon phaska" or the Pascha of the Law) which represents the nominal Jewish Passover, and the Sunday thereafter is Pascha. The dates repeat every 532 years, but the calculation is simple.

This simplicity served the practical purposes of the early Church. It was achieved after much controversy, and was accepted by all who call themselves Christian until Pope Gregory's reforms. It was the unmarred heritage of all Orthodox Christians until 1924. The ancient astronomers who developed these cycles, as well as the Fathers of the Church were aware of the slight inaccuracies, but the calendar admirably served the Orthodox Church for so many centuries. It never presented any hardship to the farmers who use the calendar, for it is immaterial what the number on the calendar was that marked spring planting or the fall harvest, so long as it was consistent. It would have presented no hardship to modern civilization to have retained the Julian Calendar, because it makes no difference to engineering and commerce whether Christmas is celebrated 13 days earlier or later.

The fact that we follow a different calendar (almost all Orthodox still follow the Traditional Paschalion), from that followed by the world around us is good. It marks us out as a distinct and peculiar people, that "kept the ways that are hard" (Psalm ?). We have a practical advantage in keeping the Old Calendar in that we can avoid the noisy and crass commercialism that is secular Christmas, and usually, also that surrounding secular Easter.

We have no need to ask the Jews or the astronomers when the Church should celebrate her Holy Days, for it is entirely a matter for the household of the Faith to order her celebrations according to her own needs. The traditional calendar is an icon of time. It has become sanctified by centuries of use. It is not "realistic" in the same way that icons are not realistic. It is the product of a hard-won unity that is now broken by the innovators. None of the reasons set forth for adopting the Papal calendar hold water. Our purpose is not astronomical accuracy, for as we have seen, this is won at the cost of great complexity. Everything in the Church should be done decently and in order. Anything as momentous as that touching the liturgical unity of the Church should be a matter of unanimous decision of the Church, and the proposal should have been set forth properly and before all.

It was, however, introduced by force and deceit, and in disobedience to the traditions and canons of the Church. When we see the arguments, disputes, and divisions caused by the introduction of the New Calendar, can we call it a good thing? Our Saviour tells us that by their fruits shall we know them. If some change is controversial, it is the responsibility of those that propose to show that it is beneficial and needful, and if it is rejected by a large part of the Church, they should, in all humility and out of a desire not to offend the brethren, withdrawn the proposal. The harmful results of the introduction of the New Calendar, viz scandal and schism, are the fruits of disobedience on the part of the innovators.

Since the purpose of the introduction of the New Calendar was not for astronomical accuracy, but for ecumenism, for bringing Orthodox faith and practice more in line with those of the heterodox, so as to prepare the way for union with them. Those that resisted this change were therefore resisting ecumenism. Even now, one of the barriers to union with the heterodox is a different festal calendar. When the calendar innovators changed the calendar, they did not dare to change the Paschalion for fear of outright rejection on the part of the Orthodox faithful. They have thereby introduced a hybrid monster of a calendar that is neither truly New nor truly Old. Thus the liturgical unity of Orthodoxy was not entirely broken. But if the Paschalion could be changed, it would make union with the heterodox easier. Contrariwise, if the innovators would abandon their innovation, they would go a long way toward restoring unity within the Orthodox Church. It is in their power alone to do so. What has been stolen, let it be restored.

I should be very much interested to know whether those Orthodox Churches that have officially adopted the New Calendar have, in fact, adopted the "Revised Julian Calendar" with its 900-year cycle, or have merely embraced calendar reform without specification of this intricate detail, being content to use the Papal reckoning of the fixed calendar.

I should also like to point out that using astronomical observation or calculation for determining Pascha was but one of several proposed innovations to the Orthodox Church Calendar. Among others are: 1) A proposal to use the Papal Paschalion (which has been adopted by the Church of Finland and the OCA mission in Mexico), and 2) A proposed fixed day for Pascha, say, always the second Sunday of April, regardless of the phases of the moon. This latter is proposed for adoption by all Christian bodies in the world. This is not the final end of calendar innovation. One such proposal is the World Calendar, whereby the number of days in the month is regularized, and the sequence of the weekdays is broken up once (on leap years, twice) a year for the sake of keeping any given calendar date on the same day of the week year after year. This, needless to say, is totally unacceptable to any religion that celebrates a seven day week. If the Jews and the Muslims can keep their peculiar religious calendars in a modern society, why cannot we Orthodox Christians stand for our own traditions and faith? Some have already answered that question for themselves. Let us also have the courage to do so, too.  

Fr George Lardas

September, 1996