www.byzcath.org Forums General Discussions Town Hall Calendar-Easter

That would depend on the details of the implementation. If the implementation used a midnight-to-midnight day for assigning the date of the full moon, it would sometimes give a different assignment from what it would give if a 6PM-to-6PM day were used, for example.

Please re-read Isaiah 1 !!!

I have. What do YOU mean?

Try Isaiah 1:14! If the Lord God is tired of these ultimately useless astronomical conundrums, imagine the effect they have on a cranky old priest!
There already IS a common date for Pascha -- the one established at Nicea. Let's just get the best telescope man can create and observe the date as stipulated. Fr. Bob Taft, S.J., please give us more of your words of wisdom!

A problem in this and most discussions on the calendar and date of Pascha are the facile and uninformed comments that are casually thrown out in the midst of serious discussion. Don't be cranky, be informed. We don't require a Fr. Taft -- he is certainly welcome to the discussion -- we just need to study the issue as thoroughly as possible in its historical, scientific and theological facets. The acquisition of knowledge and understanding can get messy.

"There already IS a common date for Pascha -- the one established at Nicea." Everyone should hold to this but there are Pope, Patriarch and Archbishop who would fix it to make it simple and convenient for the world, for commerce and school calendars and business etc. For them the intrusion of the yearly observance of the Resurrection is to be fixed by, in effect, following the excerpt from Isaiah as though it were an absolute pronouncement. Of course that is not their motivation and a proper exegesis of Isaiah 1, putting the verse in context, reveals that he is addressing, rather, a certain class of people (four verses prior):

RSV Isaiah 1:10 Hear the word of the LORD, you rulers of Sodom! Give ear to the teaching of our God, you people of Gomorrah!

Jesus who observed the feast reckoned on the new moon of spring understood Isaiah 1 correctly and even celebrated the feast with fervor and anticipation:

RSV Luke 22:15 And he said to them, "I have earnestly desired to eat this passover with you before I suffer;

Our science, astronomy, and telescopes are already and for some time have been more than good enough. Some details in applying and specifying the prescription that has evolved based on the decision of Nicaea are still wanting, even in using precise yearly astronomical data. There's nothing wrong in relying on modern science but it is not the only legitimate solution that it is sometimes made out to be. The 16th c. calendar reformers considered detailed calculations and chose instead, as Pope Gregory XIII specified, a traditional computus that was in perfect accord with Nicaea_I, patristic thought and the evolution of the paschalion up to that time, retaining the familiar methodology and adapting it only as necessary to achieve the required accuracy needed for a functional calendar. The Gregorian calendar is a very good calendar which is why it is so widely used, an international standard. The Gregorian paschalion is a very good -- close to the best if not actually so -- computus, faithful to the method used since Nicaea_I. It is the already existing right solution. This year we have just experienced the actual equinox, the fourteenth day of the moon and then in accord with the accepted prescription, the Sunday just past that followed, as the feast of Pascha.

So I do not agree that "the Lord God is tired of these ultimately useless astronomical conundrums." After all, He created them and us, His "rational sheep," to figure it out.

Can you provide a link to the thread you refer to?

I have worked as an astrophysicist, and I never needed the Julian calendar, or any other, for my computations on interstellar molecules. I used the Gregorian calendar to make sure I got to meetings on time.

For some long-distance computations involving dates both before and after the change-over to the Gregorian calendar, it can be convenient to do the computations entirely in the Julian calendar, or entirely in the Gregorian proleptic calendar, and convert as needed at the end. Often this will mean using the Julian calendar since that was the contemporary calendar for much of early history, or because historians have already synchronized many useful ancient dates into the Julian proleptic calendar. But this has nothing to do with which calendar is a better approximation to the Spring equinox tropical year, or with which calendar has more accurate lunar tables.

People often confuse the "Julian Calendar" with the "Julian Date", which has several different meanings.

Some branches of science use the "Julian Day" to have a single count of the days since the creation of the world, using 12h Jan 1, 4713 BC as the starting point.

Others use it as a simplified way to count the days, using January 1 as day 1 (i.e., 2016-001) and December 31 as day 366 (2016-366). But this is more properly called the "Ordinal Date".

https://en.wikipedia.org/wiki/Julian_day
https://en.wikipedia.org/wiki/Ordinal_date

Quite a history there. I recall but did not document that NASA's alleged use of the Julian Calendar was noted by an Orthodox bishop whose writing appeared on the calendar related page of what I refer to as the Unorthodox Unchristian Misinformation Center ( link [orthodoxinfo.com] ). It is no longer there, being perhaps too misinformed even for that site's taste -- or maybe I found it on a different site.

The canard has quite an interesting history on this forum. It is a study of the inability to communicate, persuade, reason and comprehend when the result, e.g.
has already been decided. In chronological order:

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As I understand, the beginning of the Julian period was not the supposed date of the creation of the world, but the day on which, according to Scaliger's calculations, the 28-year solar cycle, the 19-year lunar cycle, and the 15-year cycle of the indiction all had a simultaneous beginning.

It is true that the 28-year solar cycle presupposes a Julian year of 365.25 days. It is also true that, together with the Julian day count, some astronomical computations use the Julian century of 36525 days as a time-unit. But still this has nothing to do with the accuracy of the Julian calendar. The Julian calendar predicted an equinox on April 3rd. The Gregorian calendar predicted it on March 21. It was on March 20 UT. The Gregorian approximation was closer to the exact result. The Gregorian calendar predicts a full moon between sunset April 20 and sunset April 21 this month. The Julian calendar predicts a full moon between sunset April 25 and sunset April 26. Exact computations predict the full moon at 5:24 UT on April 22. The Gregorian approximation is closer to the exact result.

An example of the use of the Julian calendar in astronomical computations is Simon Newcomb's "On the recurrence of Solar Eclipses, with tables of Eclipses from B.C. 700 to A.D. 2300", published in Astronomical Papers prepared for the use of the American Ephemeris and Nautical Almanac, Washington, 1882, pp. 1-56.. Newcomb's tables are in the Julian calendar presumably as a matter of convenience. The user of the tables thereby avoids the discontinuity at the Julian-to-Gregorian changeover. Certainly it has nothing to do with the accuracy of the Julian paschalion. If we used the Julian lunar tables we would never predict eclipses accurately.

Today is the 14th if Nisan ("passover") in the Julian lunar calendar.

Here is a recent article on the topic of the Julian computus:

https://publicorthodoxy.org/2016/04/25/some-common-misperceptions-about-the-date-of-paschaeaster/

On an earlier thread here, Azarius wrote:


The average lunar drift is roughly one day in 300 years. The exact value rises and falls. In terms of days per year this is slower than the solar drift in the Julian calendar, but in proportion to the length of the full period, solar year or synodic lunar month, the lunar drift is faster. The present-day discrepancy is a little more than 4 days, so in about a thousand years, Julian Easter will always fall in the last week of the moons phases, rather than in the third week where is ought to be.

In the same post, Azarius also linked to this page, [staff.science.uu.nl] which compared the Julian Easter date in late antiquity and the early middle ages to the date of 15 Nisan that would have been computed on the modern-day Rabbinic calendar. The difficulty with this is that the traditional date of A.D. 359 for the promulgation of the Rabbinic calendar is almost certainly wrong. Some of the rules (such as the 19-year intercalation cycle, or the fixed lengths of the months from Adar to Tishri) that later became part of the Rabbinic calendar may date to that time, but the detailed mathematical work on the Rabbinic calendar did not begin until the 700s, and the details did not reach their present-day form until the 800s, according to Sacha Stern's reconstruction of the history. So only the last of the dates shown in the table, 743 and 783, can be asserted with much confidence, though all of the dates remain possible dates for 15 Nisan that might have been arrived at by means other than the modern-day computation.

Julian and Gregorian Easter are on the same date this year, but Julian and Gregorian Passover (14 Nisan) are different as always.

The Gregorian Passover (14 Nisan / Paschal full moon) this year is on April 11.
The Julian Passover this year is on April 15.

For comparison:

The Rabbinic Jewish Calendar's 14 Nisan is on April 10.
The Samaritan Calendar's 14 Nisan is also on April 10.
The astronomical full moon is on April 11 (Universal time)

I thought it about the time of year for the annual "battle of the calendars" to occur. If not a battle, at least the annual upsurge in interest in the two dating systems. I have decided to take the easy way out - are you listening Alice? I will have two chocolate bunnies this year to celebrate the two calendars.

Whenever I read the broadsides on the dating of Pascha, I think of Isaiah's opening salvo: "Your new moons and sabbaths and great day I cannot endure. Fasting and holidays as well as your new moons and your feasts my soul hates! For who asked these things from your hands?