Usage of the Julian Calendar

[JMJ_coder]

I have two questions regarding the usage of the Julian calendar.

1. In the calculation for the date of Easter it seems that a specific date is used (e.g., March 20) for the vernal equinox as opposed to the date when the sun crosses the equator (e.g., when there is ~12 hours of day and night). Is this correct, and if so why?
2. Why is the Julian calendar still used since it is demonstrably flawed in some respects? I’m not saying that the Gregorian calendar is 100% accurate (since it still fails to account for some things), but it is a giant step in the right direction. For example, what will happen if the Lord delays in coming for a great deal of time and some many centuries down the road those using the Julian calendar find themselves celebrating Christmas in June and Easter in September?

 

[runningdude]

It is only used for calculating religions dates by Churches that do not recognize the Pope’s authority to change the calendar. Some of these churches actually got together to create “revised” Julian calendar that just-so-happens to correspond to the Gregorian calendar for the next several thousand years.

If the calendar is properly calibrated to match the solar year, the equinox will always fall on the same date. The original Julian calendar is out of calibration by about 10 days due to inadequate leap years. It is still used to calculate Easter, as it is the most sacred of holidays, which is why the “equinox” doesn’t actually fall on the equinox. Less important holidays are calculated using the revised calendar.

 

[Vico]

I have two questions regarding the usage of the Julian calendar.

1. In the calculation for the date of Easter it seems that a specific date is used (e.g., March 20) for the vernal equinox as opposed to the date when the sun crosses the equator (e.g., when there is ~12 hours of day and night). Is this correct, and if so why?
2. Why is the Julian calendar still used since it is demonstrably flawed in some respects? I’m not saying that the Gregorian calendar is 100% accurate (since it still fails to account for some things), but it is a giant step in the right direction. For example, what will happen if the Lord delays in coming for a great deal of time and some many centuries down the road those using the Julian calendar find themselves celebrating Christmas in June and Easter in September?

1. The Julian Calendar dates from AD. 325 and the Spring Equinox was arriving on March 21st then. When the First Ecumenical Council met in Nicea to settle the Pascha date, they adopted the Julian Calendar and decided that Pascha will be observed on the first Sunday after the first full moon after March 21st, and also independent of Jewish Passover. March 20 was the vernal equinox in 325 A.D. and Sunday was March 21, so March 21 was chosen.
2. Because the decision was made by an ecumenical council, some of the churches will continue to use that agreed upon date. Until all the churches can agree again, then the drifting of one day per 129 years will continue to introduce a difference.

 

[dvdjs]

1. The Julian Calendar dates from AD. 325 and the Spring Equinox was arriving on March 21st then. When the First Ecumenical Council met in Nicea to settle the Pascha date, they adopted the Julian Calendar and decided that Pascha will be observed on the first Sunday after the first full moon after March 21st, and also independent of Jewish Passover. March 20 was the vernal equinox in 325 A.D. and Sunday was March 21, so March 21 was chosen.

Actually the council did not pick a day for the equinox, not calculate Pascha following some selected date, it picked the equinox, as determined by astronomical observation. The emperor even suggested that all follow Alexandria in the reckoning, since they had the most advanced astronomers. That suggestion was ignored, already in the early years after the council.

 

[Vico]

Actually the council did not pick a day for the equinox, not calculate Pascha following some selected date, it picked the equinox, as determined by astronomical observation. The emperor even suggested that all follow Alexandria in the reckoning, since they had the most advanced astronomers. That suggestion was ignored, already in the early years after the council.

A complex matter, since there the decision of the council was redacted. The OCA site has this from *“The Council of Nicea,” in The Church of the Ancient Councils: The Disciplinary Work of the First Four Ecumenical Councils,*St. Vladimir’s Seminary Press, 1996, Crestwood, NY, pp. 19-26.We can, therefore, reconstruct the elements of the decision of the first ecumenical council on Pascha in the following way:INDENT This feast must be celebrated on the same Sunday by all the churches.
(2) It must take into account the full moon that follows the vernal equinox.
(3) Consequently, the eastern churches who followed the Jews in calculating the date must abandon this usage.
However, the council did not enter into details of the method of calculation and, therefore, did not impose the use of the nineteen-year cycle. As Professor D.M. Ogitsky correctly notes, a detailed and exhaustive ordering of all the technical aspects of the computation of Pascha (including the problems raised by the inexactness of the Julian calendar) was not in the competence of the council. [55]

oca.org/holy-synod/statements/archbishop-peter/concerning-the-date-of-pascha-and-the-1st-ecumenical-council
[/INDENT]

 

[dvdjs]

A complex matter, since there the decision of the council was redacted.

Although the original statements of the council are not preserved, the promulgation letter of the emperor is - and it summarizes the prescription clearly.

(1) This feast must be celebrated on the same Sunday by all the churches.
(2) It must take into account the full moon that follows the vernal equinox.
(3) Consequently, the eastern churches who followed the Jews in calculating the date must abandon this usage.

This is excellent. There is no need for any of the various cyclic approximations, or even a calendar that does anything more that keeps track of the days and weeks. Or any linkage whatsoever to the date of Passover. Perfect.

 

[JMJ_coder]

(2) It must take into account the full moon that follows the vernal equinox.

But, doesn’t that bring us back to the original question? How is the vernal equinox determined? Is it a set date (e.g., March 20/21) irrespective of the solar position? Or is it based off of an astronomical/solar calculation of some kind?

 

[dvdjs]

But, doesn’t that bring us back to the original question? How is the vernal equinox determined? Is it a set date (e.g., March 20/21) irrespective of the solar position? Or is it based off of an astronomical/solar calculation of some kind?

Are you asking about practice, or canon?

It was clear from the writings and actions surrounding the council that “vernal” equinox" meant, and thus presumably still means the astronomical vernal equinox. At that time the actual equinox occurred n Mar 21 of the civil calendar - although the civil calendar still marked it as Mar 25. Astronomy was not so good at that time - Rome reckoned it in the year after the council as Mar18. Eventually, calculations - cyclic algorithms linked to a fiducial date/year, came to be used instead of observations. Ultimately it became clear that that was not working. So, after a lot of observations, a new calendar was proposed, and adopted over time in the West, with a shift that put the actual equinox back onto Mar21, thus preserving the cycle of feasts as at the time of the first council. Once this correction was made, it was back to calculations for succeeding years.

The Aleppo proposal of some years ago recommends that go forward with astronomical reckoning of the vernal equinox.
oikoumene.org/en/resources/documents/wcc-commissions/faith-and-order-commission/i-unity-the-church-and-its-mission/towards-a-common-date-for-easter/index
That proposal has some support in the East, and could be accepted without notice in the West. But there is no mechanism to move it forward.

 

[Vico]

But, doesn’t that bring us back to the original question? How is the vernal equinox determined? Is it a set date (e.g., March 20/21) irrespective of the solar position? Or is it based off of an astronomical/solar calculation of some kind?

The Vernal Equinox methodology was not specified, but tables were actually used.

"The full moon involved is not the astronomical Full Moon but an ecclesiastical moon (determined from tables) that keeps, more or less, in step with the astronomical Moon.

The ecclesiastical rules are:

• Easter falls on the first Sunday following the first ecclesiastical full moon that occurs on or after the day of the vernal equinox;
• this particular ecclesiastical full moon is the 14th day of a tabular lunation (new moon); and
• the vernal equinox is fixed as March 21."

See US Naval Observatory: aa.usno.navy.mil/faq/docs/easter.php

Today “…the vernal equinox, which is established as 21 March and on which the date of Easter depends, falls in the Julian calendar on a day which under the Gregorian calendar is 3 April.”

oikoumene.org/en/resources/documents/wcc-commissions/faith-and-order-commission/i-unity-the-church-and-its-mission/frequently-asked-questions-about-the-date-of-easter