Tuesday, September 18, 2018

On Calendar Drift

Leap Years: we can do better
standupmaths | 23.II.2016

1:53 Egypt had a year of 365 days only ... a calendar drift every 4 years (and some want me to swallow that Osiris was born in Egyptian version of December 25th ... duh!)

Thanks for a video documenting that calendar drift is sth which some guys lived with ....

2:09 Actually, Roman calendar had a very interesting story. I'll break it down in the comments under this one.

Stage one, winter plus 10 months, March through December (and after June you have Quintil and Sextil which were later renamed July and August).

Since each month is a lunar month and since winter can be either two or three lunar months depending on when December ended last time and how moon phases fit in or not with solar years, there is constant calendar drift and no calendar drift at all overall, since it is corrected from year to year by the length of "winter".

Stage two - 12 lunar months. Calendar drift is imminent.

Stage three (not sure how long stage two lasted) - 12 lunar months plus some years a leap month, Mercedonius, inserted with February ...

Stage four, Romans no longer sure which years to insert Mercedonius.

AND stage 5, Julius Caesar solves the problem.

2:16 needs of calendar not top priority - you may say that again (and even so, they were annually reelected, so leap months affected mandate length!).

Heard of Punic Wars? That is when the Roman calendar went chaotic about when to insert or not insert Mercedonius.

(Yes, the part about mandate length was also appropriate ....)

2:39 No, Julius Caesar was not fixing one day drift every four years by putting in an extra year every four years.

Or, not in Roman calendar.

The facts are that Julius Caesar was facing a somewhat different system than Egyptian year, heard of the Egyptian 365 days year and of its by then known weakness, and imported it with the weakness fixed.

It's not Roman years that were drifting 1 day every four years prior to 46 Before Christ.

4:57 In fact in 1583, there was a reaction from Byzantium, from Phanar, by now under Turkish occupation, but still.

Popes do bulls. Patriarchs of Constantinople do sigillia. Means, in both cases, a letter which the potentate signs with a seal ("sigillion" is that word, or its diminutive, I thought it was "sigillikon," but that may be Mandela effect - or they may have changed Orthodox wiki, and "bull" is the bubble of lead which the seal is stamped on).

And the sigillion of 1583 speaks of "atheistic mathematicians" ... I somehow don't think the then Patriarch Jeremias II Tranos (1572–1579), restored for first time (1580–1584) meant you, even if I suppose some of you are atheists. I think he meant Father Christopher Clavius SJ.

SJ means, he was a Jesuit. I am not sure Father Christopher Clavius appreciated being called an Atheist by Jeremias II Tranos ....

One of the things the sigillion says is, if you use the Gregorian calendar for either Easter (mobile feasts) or Menologium (date fixed feasts), you are not a Christian.

I don't think Father Christopher Clavius or Pope Gregory XIII agreed.

5:09 "and everyone finally was on a new calendar"

No. Not the Eastern Orthodox in Turkish Empire. Also, not the Eastern Orthodox in Russian Empire.

You know why the October Revolution happened in November? Because it takes the Julian calendar still in use in Russia and other former USSR states (excepting the Baltic ones) another by now 13 days to go from October to November.

Fun or less fun fact : John Paul II (who was not so good at persuading Catholics to change things, since some including me consider him an Antipope - he has not persuaded us) visited the Synagogue of Rome on April 13 of 1986.

Now, you may have heard the Chernobyl disaster was on April 26 ... but in Ukraine it was, that day, April 13 ...

Considering how many died in that disaster, perhaps the fact is more like "less fun" ...

I missed one reference.

Numenorean calendar ... Tolkien prided himself on having constructed one (in other ways incompatible with our feasts, and so unusable, but not to the fictitious Numenoreans in .... Atlantis? sth like that?) which was slightly less prone to calendar drift than Gregorian calendar ...

You never mentioned that. If you are not a Tolkien fan, is Adam Gutsche, perhaps?

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