From Julian to Gregorian Calendar | Hacker News Reader

From Julian to Gregorian Calendar

timeanddate.com

56 pointstecholic31 comments

I was glad to see that this included my favorite calendrical fact: the existence of February 30th, in just one year in Sweden.

It misses another good one, which is what happened in Alaska. Alaska's transition from Julian to Gregorian happened when ownership of the territory transferred from Russia to the United States. This also involved moving Alaska to the other side of the International Date Line (or more correctly, moving the Date Line to the other side of Alaska). The net effect was that, in Alaska, Friday, October 6th, 1867 was followed by Friday, October 18th.

If you ever read Umberto Eco's novel "Foucault's Pendulum" this is a key plot point. Specifically some shadowy "conspiracy" group was set to meet, but the meeting never happened because some countries had revised their calendar and some hadn't so they missed each other. Its a great novel about secret societies, conspiracy theories, and peoples willingness to believe them.

Is this a spoiler for the novel?

It's not the kind of novel where knowing something like that will make a difference.

Yeah, there are hundreds of little esoteric facts like that contribute to the conspiracy theory. So no spoilers.

Fun fact: astronomers (and Nasa) use the Julian calendar for events (for example eclipses) before october 1582. You'd think they use UT, but they don't, so you can match historical dates with celestial events. Also worth noting, astronomical year numbering has a year 0, whereas BC/AD system does not, so that year 0 is 1 BC.

You have to make time corrections when you program something related to astronomy. In most things we program, UT is an absolute on which we can rely, but when we go very far away in the past it's not that clear anymore.

...and then there's Julian Day (JD).

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

... and then there's JD combined with Delta T https://en.wikipedia.org/wiki/%CE%94T

Unix seems to handle it well:

$cal 9 1752

    September 1752
 Su Mo Tu We Th Fr Sa
        1  2 14 15 16
 17 18 19 20 21 22 23
 24 25 26 27 28 29 30

there is a Bug on the man page, which has more to do with "what country are we in" BUGS The assignment of Julian--Gregorian switching dates to country codes is historically naive for many countries.

ncal allows me to specify the country, so even though I'm in the US I can get the following:

  $ ncal -sES 10 1582
      October 1582
  Mo  1 18 25
  Tu  2 19 26
  We  3 20 27
  Th  4 21 28
  Fr 15 22 29
  Sa 16 23 30
  Su 17 24 31

(Alas, ncal -sSW 2 1712 doesn't get February of 1712 right in Sweden...)

"Switch Took More Than 300 Years"

I sure hope the complete switchover from IPv4 to IPv6 also doesn't end up taking that long.

The Serbian Orthodox Church still hasn't switched from the Julian calendar. So now their religious holidays like Christmas are a couple weeks off from the rest of the world and will continue diverging.

Isn't that all Orthodox churches, not just the Serbian?

My wife's a bit of a Russophile. So in years where we forgot to do the holiday shopping, we exchange gifts on Russian Christmas (i. e. January 7, Gregorian). Or, if we're really forgetful, Russian New Year.

Curiously, January 7 is also when many Spanish families exchange gifts, supposedly as a celebration of the arrival of the Magi/Three Wise Kings (who brought gifts to Jesus).

This is much to the annoyance of Spanish kids with foreign friends :)

It's amusing that Twelfth Night is so little known, despite the play, the "12 days of Christmas", and so on.

I suspect if you asked most people when the 12 days of Christmas are, they'd say they were December 14-25 (or maybe even 13-24). After all, that's when you buy the presents!

That holiday is Epiphany, which is a separate holiday (and I believe actually falls on the 6th of January on the Gregorian calendar).

Yes, but that is a coincidence. Russians celebrate Christmas on December 25th like everyone else (except some norther Europeans, we celebrate on the eve), it's just that their view of when it is December 25th differs.

Yes, it's a coincidence, that's why I find it curious :)

Christmas in Russia is celebrated on 7 January

My point was that no, the holidays are celebrated on the same dates throughout the Christian world, but depending on which calendar you use those dates fall on different days. Today for example it's August 10th in many Orthodox churches, while most others would say it's the 23rd.

Not all. Some have switched to Gregorian calendar.

At least in the U.S., the Antiochian and Greek Orthodox churches primarily use the Gregorian calendar (e.g., Christmas is on Dec. 25). However, Pascha and its related feasts are still determined using the Julian calendar which happened to fall on the same day as the Western Easter this year (Apr. 16).

Christians agree that Easter is computed using a lunar calendar, however, various sects use different methods for computing lunar leap months. Passover is also on the lunar calendar.

Easter (or Pascha/some derivative as it's called in most non-English countries - which comes from Passover) is basically Passover + a bunch of days (remember the story of the Crucifixion then Resurrection).

My mistake. For some reason I was thinking there was still some component of the Julian calendar used with the calculation even though it is lunar based.

(not so) interesting fact: Russians celebrate new years much like we celebrate Christmas (gift giving, family meal etc;)

This is due to the Soviet Unions downplaying of religion, but understanding the need of a yearly get-together.

So, my girlfriend celebrates NYE as if it were Christmas, Christmas is seen as "not really important" and she didn't even have a concept of Christmas being on Dec 25th (which, consequently was when she was born herself)

Russians currently celebrate Christmas by being mostly drunk between Orthodox Christmas and Twelfth Night.

Nah it depends. Romania is also an Orthodox Christian country but uses the Western calendar. They still have Easter on the same day because that's calculated separately, but they celebrate Christmas on different days - Dec 25th vs Jan 7th.

It's basically the slavic orthodox countries that use the old calendar, plus certain groups that have more or less broken out of other churches. The monasteries on Athos also use the old calendar, even the monasteries that belong to new calendarist jurisdictions. A fun fact is that visas to Athos, which is a semi-autonomous island in Greece where only men are allowed (not even female animals!) and that prince Charles loves, are issued in the Julian calendar.

It's worth noting that even most new calendarists, like the Greeks, still celebrate Easter at a different date than the Catholics.

The calendar question is extremely infected and especially the Russians consider it a very crucial issue.

https://en.wikipedia.org/wiki/Mount_Athos

That's cool, I hadn't ever heard about Sweden's double-leap years.

I did some research on calendars a while back, and notably, the conversion to Gregorian had a lot of religious overtones. Here's what I wrote about it:

https://webcache.googleusercontent.com/search?q=cache:xrRtua...

(edit ...and Google cache is being ornery right now.)

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