Talk:Gregorian calendar/Archive 3

Something is fishy here, church wouldn't approve 10 day slip!
> A deletion of ten days was made, when switching to the Gregorian calendar.

Looks unbelievable. The church would never do that. The Bible says God created the world in six days and rested on the 7th. If the first sunday mass after the reform would not be exactly seven sunset and seven sunrises after the last sunday mass held before the reform, it would be invalid, because that would not be on the seventh day any more. <--> Jesus himself established the celebration of the day right after sabbath, on every seventh day.

Thus, if the ten day slip is true, in fact all "sunday masses" held since the reform are fake and invalid and it looks like hundreds of millions of people, who got null and void communions, are burning in hell just because of this mistake by the catholic church. Plain impossible.

If the church had to reform the calendar, it would definitely wait a little longer, until the difference becomes exactly two weeks and switch then, so the first Sunday Mass held after the reform would still be exactly (N x 7) days after Jesus Christ established the Sunday. Why would the RC church run to make a 10 day switch, when it already had 1-1/2 millenia behind its back? They could wait a few centuries more.

Did anyone honestly investigate this issue? I think if true, this must be the true reason the orthodox christians stick with the old calendar, not the western papal - eastern autokefal authority clash.

Thanks for your attention, Sincerely: Tamas Feher "etomcat@freemail.hu"


 * The ten-day slip is true. But you're also right that the church did not want to interfere with the 7-day cycle of the week, so that cycle was not changed: Thursday October 4, 1582 (Jul) was followed by Friday October 15, 1582 (Greg). The last sunday mass in the Julian calendar was on Sunday Sep 30; the first in the new calendar was Sunday Oct 17; these dates were precisely 7 days apart.


 * So this means that the day of the week was the same in both calendars for a certain day, but not for a certain date (e.g. October 15 1582 was a Monday in the Julian calendar, but a Friday in the Gregorian). Eugene van der Pijll 20:50, 23 Mar 2005 (UTC)

Except in Alaska, which switched sides of the International Dateline and therefore had 48 consecutive hours of the same day of the week.
 * Alaska was not a British colony when the dates changed in the British Empire, you are presumably talking about a different time and the change from the Russian Orthodox calendar to the Gregorian calendar. --Philip Baird Shearer (talk) 13:21, 15 January 2008 (UTC)

Slowing of the earth and the effects of global warming on same
This statement was made:
 * However, recent evidence suggests that melting of glaciers (resulting from global warming) may create sufficient movement of water from high altitudes to the oceans to reverse the slowing, to satisfy the law of conservation of angular momentum.

It lacks a citation. I believe that's because it is nonsense: as glaciers melt, water is more evenly distributed over the globe, so there is more water around the equator than there was before, so to maintain the same angular momentum, the earth would have to slow even more, not speed up. (You can do the old spin-in-your-chair-and-put-your-legs-out test if you've forgotten what moving mass away from the axis of revolution does to rotational speed.) I believe one of the guidelines for editing is "Be Bold," so I am going to remove the above comment, since it seems obviously false to me. My apologies if my physics has failed me. If you add it again, maybe go find a reference this time.

Pqrstuv (talk) 03:04, 1 January 2008 (UTC)


 * Because the editor used altitude, not latitude, he may have thought that the transfer of water from high altitude melting mountain glaciers to low altitude oceans would speed up Earth's rotation. Unfortunately, it is not the location of mass relative to sea level (or the center of the Earth) but its distance from Earth's axis which influences Earth's rate of rotation. So even though the melt water spreads out as a thin sheet over the oceans, more of that sheet would end up in tropical oceans that are much further from the axis than the orginal glaciers, most of which are in Alaska or Patagonia.


 * The "recent evidence" is Jean O. Dickey et al., "Recent Earth Oblateness Variations: Unraveling Climate and Postglacial Rebound Effects" Science 298 (2002) 1975-77 (discussed at Earth's bulging waistline blamed on glaciers, oceans) and associated American Geophysical Union articles. These authors state that Earth's J2 oblateness increased (flatter poles, bulging equator) beginning 1997/98, requiring them to propose plausible causes, which included ice/water transfer. Although they never state that the oblateness increase should have increased Earth's slowdown rate, that would indeed be the result.


 * Nevertheless, since 1972 the length-of-day (LOD) has been getting smaller, hence Earth's rotation has been speeding up ( (1.28 MB)). That file implies that the speedup is due to the transfer of core angular momentum. This speedup would need to continue for another decade or more before a negative leap second would be needed (UTC follows TAI). — Joe Kress (talk) 07:43, 13 January 2008 (UTC)

Beginning of year
This section details changes made before the Gregorian Calendar was adopted. Should this infomation be elsewhere? Also the table of new year change date may be mistaken by a careless reader to be table of Gregorian Calendar adoption dates. I think the table should be moved elsewhere such as Julian Calendar or New year.

Karl 27 Oct 2005


 * The table and text are mine. I put it here to show that the Gregorian calendar did not change the beginning of the year to January 1 as many think. It shows that most Western European countries had already adopted January 1 as the first day of the numbered year before the Gregorian calendar was promulgated. "Careless readers" should be disuaded by a caption at the head of the table such as "Adoption of January 1 as beginning of year". &mdash; Joe Kress 02:27, 28 October 2005 (UTC)

A table that only shows the dates that various countries adopt 1 January new year fails to make this point. I'll may add a column to show the Gregorian calendar adoption date the different or not between the two would demonstrate the point.

Karl 28 Oct 2005


 * To Oz1cz: I gather you disagree with Mike Spathaky since don't think Denmark and Sweden changed the beginning of their numbered year to January 1 at the same time that Prussia did (1559). Furthermore, you give an extremely early date for Denmark (between 1300 and 1349), but don't think that Sweden changed at the same time. Are you sure that you are not inadvertently refering to the period when it named January 1 its New Year's Day? The two are not the same. I remember reading a source that had its earliest year about 1450, but nothing earlier. What is your source? &mdash; Joe Kress 06:15, 10 November 2005 (UTC)


 * My source is a Danish book, namely R.W. Bauer: "Calender for Aarene fra 601 til 2200", which is a major source for calendar information about Denmark. It is old (first published in 1868) but it has been reprinted several times later (in 1993 as ISBN 87-7423-083-2).


 * Here is what that books says: "Denmark usually began the year at Christmas, although also 1 January and 12 August have been used. In the library of Strasbourg there is an old almanac written in runes in which the year starts on 1 January. From the beginning of the 14th century the beginning of the year has always been 1 January."


 * The book also claims that 1 January has been the start of the year in Sweden since the beginning of the 16th century. I missed that yesterday when I updated the page, so it didn't make it into the table.
 * --Oz1cz 22:28, 10 November 2005 (UTC)


 * This article states; "The Ancient Romans had begun their years on 1 January." Yet the Roman calendar article states otherwise; http://en.wikipedia.org/wiki/Roman_calendar#History_of_the_calendar It shows that in 713BCE the months January and February were added to the end of the year after December. This position also explains the use of September(7) October(8) November(9) and December(10) as the names of those months. They were named based on their ordinal position from March the beginning of the year.
 * --User:Strider22 2007-11-13 —Preceding comment was added at 05:08, 13 November 2007 (UTC)


 * According to Bonnie Blackburn & Leofranc Holford-Strevens (see References in article) page 6, "New Year's Day. Although the Romans knew that their year had originally begun with *March, the name Ianuarius is not appropriate to an eleveth month; the New Year festivites seem too well entrenched to have been moved in historical times, and if the first written account of the Roman calendar, put on public display in the temple of Hercules and the Muses c.179 BC…had indicated a March beginning, our sources must have told us, such was the Romans' interest in their calendar...." I take this to mean that the change from a March new year to a January new year occured in prehistoric times, and by the time the Gregorian calendar was adopted in the middle ages, Rome considered 1 January to be New Year's Day. --Gerry Ashton 14:08, 13 November 2007 (UTC)

I think there's a lot of confusion about this, which I'm not totally able to clear up. There is evidence (Samuel Pepys' diary) that English people believed Jan 1 to be the start of the year. I think there's too much bland acceptance that 25 March was New Year's Day (in England at least). This would make a rather strange calendar in practice. Can anyone produce a calendar that shows this??? Is this rather a minor tradition existing alongside the calendar year - like our current financial/fiscal year - that has been preserved by antiquarian, eccentric interest to the extent that in presentation of the issue it distorts the reality of the case? Doesn't it seem to be true that the Roman tradition of starting the year on Jan 1 has continued to the present day?--Jack Upland (talk) 10:31, 7 January 2008 (UTC)


 * The article Calendar (New Style) Act 1750 explains that the start of the year was a matter of law. Of course, by 1750 England was an important trading nation, so many people would have used January 1 while dealing with foreign trading partners. I vaguely reading that there was some sort of New Year celebration on January 1, despite the fact that March 1 was the legal new year. --Gerry Ashton (talk) 19:39, 7 January 2008 (UTC)

I have a strong suspicion that we approach the concept of New Year's date in a much too rigid fashion. Living in the 21st century, we are accustomed to governements and standardisation bodies laying down strict rules for all kinds of things. I think it highly likely that the the concept of New Year's day was much more fluid and ill-defined a few hundred years ago, with different regions, different organisations and even different people celebrating New Year and bouncing the year count at various dates. Is it not, perhaps, a mistake to claim rigidly that nation X changed to 1 January in the year Y? Does the table in the article actually give a wrong impression of something fixed, when, in fact, things were quite fuzzy? (Or am I making no sense at all?) --Oz1cz (talk) 08:08, 8 January 2008 (UTC)


 * You've got a point, but you're exaggerating it. They did have laws, bureaucracy etc. After all there was an Act of Parliament to change the legal situation.  The point is that just as we have different definitions of the year (fiscal, financial, tax, school, church etc) so did they. Do we have any record of people celebrating New Year in March???  Do we have any evidence that people considered the "legal year" as the "calendar year"? In fact, the articleCalendar (New Style) Act 1750 cited above quotes the Parliament saying the 24 March start "differs ... from the common usage throughout the whole kingdom" i.e. the legal year was not used for everyday purposes.--Jack Upland (talk) 20:38, 10 January 2008 (UTC)


 * Jack is essentially correct. The primary source of confusion is that the modern calendar year is the same as the modern numbered year. Calendar year means the order in which the months are displayed. This has been January through December since at least the time of the Decemvirs in 450 BC (Roman Republican calendar c.60 BC). This order did not change during the Middle Ages even though the first day of the numbered year in Western Europe was March 25 (Anunciation), Easter-Eve (in France), or December 25 (Christmas). These days were celebrated as solemn religious 'festivals', not as New Year's Day. The beginning of the calendar year was called New Year's Day, at least in England, and was celebrated as a merry New Year's festival. In French, étrennes means a New Year's gift.


 * A good medieval calendar is the Brandeis Book of Hours (in Latin, 15th century, Flemish). Its calendar is on pages 1r-12v in the order January to December (half month per page). A transcript of all its calendar pages is in the Kalendarium. The history of exchanging gifts on the Kalends of January, New Year's Day, is in Past presents: New year's gifts at the Valois courts, CA. 1400 by Brigitte Buettner. This New Year's celebration is the subject of the January illumination of the most famous medieval manuscript of all, Les Très Riches Heures du Duc de Berry (the very rich hours of the Duke of Berry, c.1416).


 * Reginald Poole mentioned a similar exchange of gifts on New Year's Day by King Henry the VIII and his court, so it was officially sanctioned in both England and France. France finally merged its two official years by legally adopted New Year's Day as the beginning of its numbered year on January 1, 1564, well before it implemented the Gregorian calendar on December 20, 1582. England was a little late, not merging its two official years until it recognized New Year's Day as the start of its numbered year on January 1, 1752, only a few months before it implemented the Gregorian calendar on September 14, 1752. — Joe Kress (talk) 02:35, 13 January 2008 (UTC)

"Essentially correct" or totally correct? Sorry, but it's a valid question.--Jack Upland (talk) 08:24, 13 January 2008 (UTC)


 * I have just come across this page that says "Nepal New Year's Day: 14 Apr 07". I suppose for many cultures around the globe the new year and the calendar year still do not coincide. --Philip Baird Shearer (talk) 13:27, 15 January 2008 (UTC)


 * That's from the Nepal Sambat, a lunar calendar. Rosh Hashanah, Islamic New Year and Chinese New Year are better-known lunar New Years. jnestorius(talk) 14:13, 15 January 2008 (UTC)

I'm sorry but that's totally irrelevant and totally intellectually uninteresting. The earth revolves around the sun. Hence the year. There is no cosmic starting point...--Jack Upland (talk) 09:48, 1 February 2008 (UTC)

Riots
Can anyone tell what the citation is for this?
 * Four years later, someone running for a seat in Parliament used the campaign slogan "Give us back our eleven days!", which created false stories of riots at the change-over.

Every source I can find seems to confirm that there were actually riots (including deaths in Bristol). KWH 07:49, 8 February 2006 (UTC)


 * Actually, historical researchers combing through contemporary newspapers haven't been able to find such riots. Most of this seems to have come from a Hogarth painting of ca. 1755 which depicts a heavily-contested parliamentary election in which the calendar issue was one of the slogans dragged in to attack the incumbent.  I've added a thumbnail to the article page. Churchh 15:56, 19 March 2006 (UTC)


 * Added further info on the parliamentary election, and Hogarth's depiction of it. Churchh 22:13, 7 April 2006 (UTC)

I don't buy the "no riots" argument at all. How does Hogarth's painting clear up the case? Why would an election slogan like that give the impression of riots? Yes, we should provide evidence of riots, but this simplistic argument against them doesn't wash. Unfortunately riots by their nature are not well documented...--Jack Upland (talk) 10:19, 18 January 2008 (UTC)

'Give us our eleven days!': calendar reform in eighteenth-century England in Past & Present, November, 1995  by Robert Poole looks at this in detail and concludes that it is a myth (see Page 4). I think a paragraph stating that in an article written by PP for P&P looks at all the evidence for riots and concludes that "[i]t can be asserted with confidence that the calendar riots are a myth. ... it seems to have developed, by accretion as it was turned to different purposes." If anyone can find an other reliable source then we can date the Past & Present article and add a "however in 2007 John Doe writing in a journal of history found there was evidence of rioting over the change of date in mousehole (or wherever) --Philip Baird Shearer (talk) 19:07, 18 January 2008 (UTC)


 * Sure, we should acknowledge his view but some of his argumentation is suspect:


 * Here [in the satirical journal, the World] we find evidence of "apprehension" and "clamour", but surely rather more evidence of the World's superior variety of satire, and of the cultural condescension of a confident Hanoverian elite.


 * The only eighteenth-century source for actual riots is Hogarth's famous print "An Election Entertainment", issued in February 1755, more than four years after the calendar reform Act was passed and more than two years after it was implemented.


 * In the first paragraph he really evades this issue. There was "clamour".  Couldn't there have been riots?  In the second paragraph, he is grasping at straws.  Four or two years isn't long at all - and certainly isn't significant discussing pre-20th Century history.


 * In the rest of the article he provides abundant evidence of the practical inconvenience of the calendar reform (in government, business, agriculture etc) and of its unpopularity (including "sharp practices" which resulted in people actually losing their 11 days due. Since the populace rioted regularly in this period (e.g. the Gordon riots) isn't it reasonable to think there would have been riots about this too? Of course it is hard to prove a negative (no riots) but the article actually makes them sound likely.--Jack Upland (talk) 08:59, 20 January 2008 (UTC)


 * What you are suggesting is original research. This article is a verifiable reliable source that states the riots did not happen. To state that they did one would need a verifiable source that stated that riots did occur due to the calendar change. If found then one can construct a paragraph that states In 19xx XYZ states that after reviewing the evidence no riotting occurred because of the calendar change, but a more recent article by ABC contradicted this assertion and found that riotting had indeed occurred in Manchester and where ever. Until then we can simply add the part up before the ", but ...".--Philip Baird Shearer (talk) 12:25, 20 January 2008 (UTC)

I haven't done any "original research" (shock, horror) on the issue. I merely point out that the article doesn't state definitively that no riots took place. It argues that there is no proof of such riots, but then shows there was much public discomfort with the change (i.e. logically no proof but plenty of evidence). It would be better to state that it has been generally believed that there were riots (numerous sources cited in the article) but this article disputes that.--Jack Upland (talk) 09:32, 1 February 2008 (UTC)

Corrections & question

 * I have made various corrections and tweaks. If anyone has a problem with this, please ask.
 * What is the meaning behind the blue marking of Lorraine and Nova Scotia?
 * Str1977 (smile back) 18:28, 15 January 2007 (UTC)


 * Gregorian calendar: It looks like those two areas were unique in that they adopted the Gregorian calendar, but then went back to the Julian calendar for a period of time before finally and permanently switching over to the Gregorian calendar. -- Jim Douglas (talk) (contribs)  18:37, 15 January 2007 (UTC)


 * Almost unique. Sweden did some funny business, too, tho not exactly the same.
 * And didn't it involve only part of Nova Scotia? --Hordaland (talk) 10:51, 1 February 2008 (UTC)

Auto archive
This talk page is getting a bit long. Would other editors agree with the concept of automatically archiving this talk page? If so, I will figure out how to do it. --Gerry Ashton (talk) 22:14, 8 February 2008 (UTC)


 * Yes, it is much too long, so some material should be archived. But I don't know of any way to do it automatically, because the most recent material must be retained, so which material should be archived is arbitrary. — Joe Kress (talk) 06:21, 9 February 2008 (UTC)

I'm not sure I understand your comment. There are bots that will do the archiving automatically such as User:MiszaBot. An invisible header is placed in the talk page, containing instructions to the bot. It can be set to archive any thread that has not been active in a certain number of days. So is your comment indicating you were not aware of a way to just archive the inactive threads, or were you objecting to the concept of archiving things automatically, and think some kind of judgement about the long term value of a thread should be made? --Gerry Ashton (talk) 19:23, 9 February 2008 (UTC)


 * I was not aware of those bots. They sound perfect. — Joe Kress (talk) 08:22, 10 February 2008 (UTC)


 * I've experimented with automatic archiving of my own talk page, and convinced myself I know how it works. If I don't hear any objections by 14 July 14:00 UTC I will set the page to archive threads that have been inactive for 60 days. --Gerry Ashton (talk) 07:12, 13 February 2008 (UTC)


 * Done. --Gerry Ashton (talk) 22:00, 14 February 2008 (UTC)


 * First archiving under new system has occurred. --Gerry Ashton (talk) 03:30, 15 February 2008 (UTC)

International standard
What is the international standard for the display of a calendar? Does the week begin on Sunday or Monday? -- Mufka (u) (t) (c) 17:06, 27 February 2008 (UTC)


 * There may or may not be an international standard, but any such standard would be voluntary. No country would be obliged to follow it. Also, it is likely that many countries leave the design of calenders up to individuals. --Gerry Ashton (talk) 17:35, 27 February 2008 (UTC)


 * OK, how should we handle it here? I've seen some templates with Sunday first and others with Monday first.  Seems reasonable to settle on a standard.  Would I have to bring it up at WP:VP?  -- Mufka (u) (t) (c) 17:37, 27 February 2008 (UTC)
 * I posted a question at Wikipedia talk:Manual of Style. -- Mufka (u) (t) (c) 17:51, 27 February 2008 (UTC)


 * This should be handled the same way Wikipedia handles British vs American spelling and BC/AD vs BCE/CE—both are acceptable and are determined by the first substantial editor. They should not be changed to the alternative without a good reason, for example, an article about the United Kingdom should use British spelling. In all these cases no single Wikipedia standard is possible. — Joe Kress (talk) 20:39, 27 February 2008 (UTC)

time step between the Julian-~ and the gregorian-calendar

 * 1) BC43 was the first Year of Julius Ceasar reign when the JULIAN CALENDAR started.
 * 2) Gregorian Reform include the accurateing of the Pope time-lines. It was the second time when accurate the all popes time-lines. (The first big one acurateing was at Nicea Synod.)
 * 3) ("Faitfull") "Venerable" Bede and Dionysius "Exiguus" ("Shortleg"-gimpy-) work hard and made an exact system what cant adulteration. The "week days" & "month days"  are just more than 500 years reapeting. That system was investure finaly at 1582 in all europian cauntry. The first user was the clerics after the 1000th year.

Conclusion The Julian Calendar Start not changed. The Gregorian calendar start changed minimum 2 times. This are not equals just before the first correction made of the popes time-line.


 * When somebady Used the "Sassandrian" after Alexandros Dead calendar made 323 year time step/
 * When somebady use the Julian calendar sometimes miss 8 year, sometimes miss (7+8) sometimes miss 40-44 year and this mixtures too. Because the cleric made the accurate calendar and the julan not accurate already. /

TACITUS —Preceding unsigned comment added by 84.1.164.255 (talk) 06:09, 5 April 2008 (UTC)

The Ottoman Empire and the states of the former Yugoslavia
We currently say nothing about these countries, other than mentioning "Yugoslavia" in the timeline table. I've found some detailed information here, but the English could do with some improvement. It is a very complex situation indeed, so I've made an attempt at a precis (A) and a table (B) to show what happened when with each of the countries involved. All dates are Gregorian unless otherwise indicated (but I'm sure I've made a few assumptions that I shouldn't have made), and date ranges are inclusive. This is just a start and I'm sure it can be cut down or otherwise improved. I don't want to take up too much space with an overly detailed focus on these places, but I think there's a case for some mention of it in the article. What do others think? -- JackofOz (talk) 01:55, 4 July 2008 (UTC)

Draft precis (A)
In the Ottoman Empire, the official calendar was the Islamic calendar. On 1 March 1789, the Julian calendar was introduced for civil use but the Islamic calendar contined to be used for official purposes. The Islamic year was of variable length but generally shorter than the Western year, so to bring the years into line, the Islamic years 1221 (Gregorian 11 March 1806 - 10 March 1807) and 1255 (Gregorian 17 March 1839 – 4 March 1840) were dropped from the calendar. In 1917 the beginning of the year was made 1 March (Julian), which meant leaving out the days 16-29 February 1916 (does he mean 1917?). In 1918 the beginning of the year was again changed, to 1 January (Julian). Consequently the Ottoman year 1917 consisted of only 306 days. On 1 January 1926 (Gregorian), Turkey (as the Ottoman Empire had now become) adopted the Gregorian calendar for all official purposes.

Macedonia was part of the Ottoman Empire until 1913, when it was absorbed into the Kingdom of Serbia, which was still using the Julian calendar. The end of the First World War saw Montenegro also become part of Serbia, on 26 November 1918. Four days later, on 1 December 1918, Slovenia, Croatia, and Bosnia and Herzegovina (all of which had been part of Austro-Hungarian Empire and had been using the Gregorian calendar since 1583) joined the expanded Serbia to become the Kingdom of Serbs, Croats and Slovenes (SCS). This meant that Slovenia, Croatia, and Bosnia and Herzegovina officially reverted to the Julian calendar, although the Gregorian was still widely used in practice. But this discrepancy lasted for only two months (58 days to be precise). The Gregorian calendar was officially adopted throughout the Kingdom of SCS on 28 January 1919 (Gregorian), the previous day being 14 January 1919 (Julian). Its name was changed to the Kingdom of Yugoslavia in 1929, later becoming a republic, and eventually breaking up, its constituent states all becoming independent nations.

Draft table (B)

 * Toke Norby stated that Turkey adopted the Gregorian calendar on 1 March 1917 (Gregorian), continuing to regard that date as the first day of the numbered year as it had done for over 100 years. The immediately preceding 13 days would have been 16–28 February 1916 (Turkish Julian year), which were 16–28 February 1917 for a 1 January year. So he erred when he included a 14th day of 29 February 1916, since the (1 January) 1917 was not a leap year. The next Gregorian year began 1 January, advancing the beginning of the year two months. — Joe Kress (talk) 06:47, 4 July 2008 (UTC)

Revealing the shape of Gregorian calendar adoption history
When I first read the existing chart I found it confusing, so I've edited a draft-for-comment image of the original programmed chart rendering. I've placed the national adoption dates in order, to reveal a graph shape of history. Reordering reveals a statistically attractive double watershed curve in three sections-- the initial cascade early adoption, the slower progressive adoption period, and the final cascade collapse of the anti-adopters' paradigm. Some version of the previous phrase could be added to the text. This would bring the reader's attention to the effects of historic facts in forming the graph's shape-- facts mentioned elsewhere in the article.

Maybe the original was done that way to save visual space. I'm not sure that's necessary, but if so, I have vertically compressed the draft image to the original's size. The resulting graphic text got more blurred by vertical compression. Is a shorter, wider font available to clean that up in auto-rendering of the chart?

None of the years shown are specified as "OS" in case that was ever an issue, say, in Sweden. Approaching this confusing subject as a non-expert, I would prefer a note declaring that all of the adoption years shown are valid for both calendars.

For consistency, Sweden should be dissected from the Sweden & Finland time line, rendered on a color bar with internal markers at 1700, 1712, 1753, and placed just below Protestant Germany.

Seems like a lot of countries are missing; were they all colonies? Maybe another note should state that.


 * Milo 07:01, 2005 May 1 (UTC)


 * Here is an unreliable source that might be useful for tracking down reliable sources on when countries switched from one to another. --Philip Baird Shearer (talk) 10:31, 18 August 2008 (UTC)

Prussia
Toke Norby supplies an intricate history of the adoption in Denmark, which would also have applied to Norway and Schleswig-Holstein, as Danish possessions. We need a better source to apply it to all of Protestant Germany, both to Brandenburg/Prussia, which was also Lutheran, and to the Calvinist states. Septentrionalis PMAnderson 21:01, 18 July 2008 (UTC)

10-Day Adjustment
Could someone please explain why 10 days were skipped in shifting to the Gregorian calendar. The First Council of Nicaea took place in 325, while the adjustment took place in 1582. Hypothetically speaking, if the Gregorian calendar had been used since 325, the following years would not have been leap years: 500, 600, 700, 900, 1000, 1100, 1300, 1400 and 1500. I count only nine days, yet the shift is ten. Could someone please explain this and maybe even incorporate it in the article. Juve2000 (talk) 01:43, 9 September 2008 (UTC)


 * Doggett, say "by the sixteenth century the equinox had shifted by ten days". So apparently the correction was based on the actual number of days required to place the equinox on March 21. I have not tried to do the calculations, but I would't be surprised if the fact that 9 days would have been dropped if the Gregorian calendar had been adopted in 325 is just a coincidence; if Nicaea had been held a little earlier, it would have been 10 days. --Gerry Ashton (talk) 05:14, 9 September 2008 (UTC)


 * At the time of the council of Nicea the equinox was believed to occur on March 21 in the Julian Calendar, when in fact it was usually occurring on March 19 or 20. An 11-day adjustment would be required to ensure that most equinoxes occur on March 21 in the Gregorian calendar. If you look at an equinox table you'll see that most March equinoxes occur on the 20th. I think the 10-day adjustment was a compromise between the 11-day adjustment and the 9-day adjustment as argued by Juve2000. Karl (talk) 08:10, 9 September 2008 (UTC)


 * You are probably right. The shift might have had more to do with properly alligning the vernal equinox to March 21st, and that might be why 10 days were chosen.  I found this interesting chart here which illustrates the vernal equinox dates and times around the time the Gregorian calendar took effect .  I am assuming that the First Council of Nicaea was used to determine the date for the vernal equinox, and since in 325 it fell on March 21st, that would be date they would zero in on.  Had they gone back to when the Julian calendar was adopted (back in 46 BC or so), the vernal equinox would have been on March 24th (give or take a day) since by 325 the calendar would have shifted by approximately 3 days.Juve2000 (talk) 00:07, 11 September 2008 (UTC)


 * Consider the date/time of the vernal equinox in the Julian calendar, not the Gregorian, before the 1582 reform. The Julian computus developed in Alexandria, Egypt about 310 when March 21 was chosen as the date of the vernal equinox. The average equinox in Alexandria (UT+2h) for the quadrennium 308–311 was March 19 19:43 (up to 9 hours before or after) using modern equations from Jean Meeus, Astronomical Algorithms (1991) p.166 (may have a 10 min error). This shifted 3 hours earlier to March 19 16:43 for 324-327 around the time of the Council of Nicaea. On the other hand, if we calculate the average equinox using ancient equations from Ptolemy's Almagest (via the Almagest Ephemeris Calculator), we get an average Julian equinox of March 22 07:35:24 for 308-311 and March 22 06:18:36 for 324-327. (Adjust the geocentric longitude of the Sun in the solar module to 0;00,00° and read the Julian calendar date in the calendar module.) These don't explain the choice of March 21.


 * But if we accept March 21, then when the Gregorian computus was developed just before 1576, the average Julian equinox at Rome (UT+1h) was March 10 23:42 (for 1572-75). Just after the 1582 Gregorian reform, the average Gregorian equinox at Rome was March 20 21:27 (for 1584–87). The last two are true equinoxes derived from Vernal equinox 1452–1811. Dropping ten days in 1582 located the new Gregorian equinox on March 20 (late in the day), one day before the Julian equinox of March 21, guaranteeing that Easter would be celebrated after the 14th day of the moon that was used by Quartodecimans according to Christoph Clavius, a member of the papal calendar commission and the principal defender of the Gregorian calendar:
 * "We have taken pains that in our cycle the new moons should follow the real new moons, so that the 14th of the moon should fall either the day before the mean full moon, or on that day, or not long after; and this was done on purpose, for if the new moon of the cycle fell on the same day as the mean new moon of the astronomers, it might chance that we should celebrate Easter on the same day as the Jews or the Quartadeciman heretics, which would be absurd, or else before them, which would be still more absurd." [Translated by Augustus de Morgan in A Budget of Paradoxes (1872) 363–364.]
 * Note that one day less was dropped (10 rather than 11) not one day more (10 rather than 9). — Joe Kress (talk) 03:06, 11 September 2008 (UTC)


 * Please tell me where my logic is incorrect, because there is something that I am not getting. The Julian calendar was shifting the Vernal Equinox (VE) approximately 3 days every 400 years, hence the new rules regarding leap years in the Gregorian Calendar.  As stated above, around the time of the Council of Nicaea in 325, the VE was occuring in the evening of March 21st, on average.  I assume that in 725, the VE would be occuring in the evening of March 18th, by 1125 on March 15th, and by 1525, on the evening of March 12th.  Doing some quick calculations, the VE would be shifting about 43 1/3 minutes every 4 years, so by 1581 (14 4-year cycles later), it would have shifted 9 1/2 hours to mid-morning or mid-day of the 12th.   However, as stated correctly above, by VE by then was in the evening of March 10th.  I have somehow lost 2 days.  Juve2000 (talk) 04:46, 11 September 2008 (UTC)


 * Your logic is incorrect in the assumption "around the time of the Council of Nicaea in 325, the VE was occuring in the evening of March 21st, on average." This was based on eroneous equinox times given by Ptolemy. Karl (talk) 08:09, 11 September 2008 (UTC)


 * Originally, the comment above by Joe Kress had the VE at Alexandria at around 325 as occurring on March 21st. I now realize that it has been corrected to March 19th.  I found my two days.Juve2000 (talk) 20:51, 11 September 2008 (UTC)


 * Sorry for the confusion. I calculated the Julian Date (JDN+fraction) from Meeus but then used Calendrica to convert it to a calendar date. I inadvertently copied its Gregorian date (top center field) instead of its Julian date (second field at left). When I realized my error I corrected my original post. — Joe Kress (talk) 22:19, 11 September 2008 (UTC)

Calendar seasonal error image


I am moving the image added by Baszoetekouw or 71.175.102.227 here for discussion. It still misspells "calender"—change last 'e' to 'a'. It still says "through the ages"—it must state either "over four centuries" or "over 400 years". The direction of the y axis is opposite to virtually all calendars, which always have smaller or earlier dates at the top, directly opposite to standard mathematical practice. The image displays the summer solstice, whereas the Gregorian calendar critically depends on the vernal equinox and its relationship to March 21. — Joe Kress (talk) 23:24, 14 September 2008 (UTC)


 * I have corrected the spelling and changed the subtitle to indicate 400 years rather than "through the ages". Since I did not create the graph, it is not practical to make the other changes suggested by Joe. One thing in favor of the graph is that scalable vector formats really are nicer for drawings than raster formats. --Gerry Ashton (talk) 00:50, 15 September 2008 (UTC)

Recent change to lead
I reverted a recent change to the lead, which altered a sentence to read "Years in the reformed calendar continue the numbering system of the Julian calendar, which are numbered from the traditional Incarnation year of Jesus, which has been labeled the "anno Domini" (AD) era, and is sometimes labeled known in academic fields as the "common era" (CE), othewise known as which is also often given the retronym 'Christian Era'." (Footnotes omitted.)

I have a few problems with the change. First, some academic fields use "common era", some don't. Sometimes "common era" is used in non-academic writing.

Second, the sentence has been altered to suggest that "Christian Era" exists only as a retronm for "CE" when in fact it has been in use for hundreds of years.

Third, the citation immediately following the sentence does not support the notion that "Christian Era" is a retronym for CE. If this is indeed the case, a citation should be found to support it. --Gerry Ashton (talk) 23:14, 6 October 2008 (UTC)

Minor Intro Change: "even centuries"?
Removed the parenthetical phrase "(even centuries)" from this quote in the intro:

“Every year that is exactly divisible by four is a leap year except for years that are exactly divisible by 100 (even centuries);”

For one thing, assuming that "even centuries" refers to centuries that begin with an even digit, this rule applies to both "even" and "odd" centuries; all centuries are exactly divisible by 4 and 100, so the rule applies to all of them. (Just to be clear, I'm not referring to the second part of the rule which deals with centuries divisible by 400.)

Second, the cited source doesn't actually include "(even centuries)" in the quoted passage.

Dappawit (talk) 00:49, 9 December 2008 (UTC)


 * Because other alterations have been made to the quotation, I have cut-and-pasted it from the source. --Gerry Ashton (talk) 02:33, 9 December 2008 (UTC)

Readability
The introduction is now brief and coherent, I hope; the main body seems diffuse and disorganized. Should not a major re-organization be undertaken? I would hope that readers would encounter the material they are most likely to be looking for first, for example. hgilbert (talk) 03:13, 9 December 2008 (UTC)

Netherlands Calendar change
The switch from the Julian to the Gregorian calendar was more complicated in the Netherlands than the article implied, as it varied from province to province. The provinces of Zeeland and Brabant, and the Staten-Generaal, made the switch on 25th December 1582; the southern provinces (modern Belgium) switched a week later on 1st January 1583, and the province of Holland on 12th January 1583. The province of Groningen changed to the Gregorian calendar on 21st February 1583, but reverted to the Julian calendar in the summer of 1594.

This division between the northern five provinces and the rest of the Netherlands continued throughout the 17th century. However, finally the province of Gelderland adopted the Gregorian calendar on 12th July 1700, the provinces of Utrecht and Overijssel followed suit on 12th December 1700, and Groniingen (switching again) and Friesland completed the process on 12th January 1701. Rif Winfield (talk) 20:42, 9 December 2008 (UTC)


 * That's good information. If you have a citation (I'm sure you must have because you wouldn't have just made those details up), please put it into the article. --  JackofOz (talk) 21:05, 9 December 2008 (UTC)

Proposed external link
A user tried to add a link to his website on calendar, which I reverted as spam/coi. We've been talking about it, and if it fit anywhere on WP, it would go on this page. Personally, I think it is redundant with the pdfpad.com. But he's definitely acting in good faith, easy to get along with, so I'm hoping to generate more comments here. The discussion thusfar is at Talk:Calendar. Carl.bunderson (talk) 00:00, 10 January 2009 (UTC)

Consensus seems a bit bleak. Quick question how do fellow moderators know there’s an issue that calls for their participation? I noticed several external links here in the Gregorian calendar article that in my opinion personally seem unfit. http://www.tondering.dk/claus/calendar.html is already listed among external links in calendar. http://www.norskkalender.no/ is not in English. http://www.pdfpad.com/calendars/ says DEAD LINK next to it here on Gregorian_calendar. A personal opinion I want to share about ( pdfpad.com ) is it seems deliberately ad oriented. The content it self that qualifies it to be listed among external links is seemingly disengaging and off-putting for most visitors I feel. Well I will appreciate any feed back, thanks!

Blankcalendardotinfo (talk) 10:17, 10 January 2009 (UTC) 01-10-2009 Jimmy C.


 * The one advantage of the calendar proposed by Blankcalendardotinfo over pdfpad.com is it does not seem to require Adobe Reader, which is one less potential compatibility problem. --Gerry Ashton (talk) 16:25, 10 January 2009 (UTC)


 * Shall we use both blankcalendar and pdfpad, then? And I agree, the tondering.dk doesn't really belong on this page; and since norskkalender is foreign-language, it doesn't belong at all. Whatever happens, I'll remove those two. The dead link next to pdfpad should be removed. It works for me, and I gather it does for Jimmy as well. Carl.bunderson (talk) 21:09, 10 January 2009 (UTC)


 * Yes it works for me. We should use both. And I think it’s safe to conclude Gerry’s outlook on my site is supportive (hence lesser possible compatibility issues) therefore the link to www.blankcalendar.info should be included. Blankcalendardotinfo (talk) 09:20, 13 January 2009 (UTC) Jimmy C.


 * Done. Carl.bunderson (talk) 09:44, 13 January 2009 (UTC)

The lead
"The Gregorian Calendar is an international civil calendar."

I hope this helps, it removes any bias for or against the calendar. It's terrible bad form to make the first sentence a quote, and I feel this wording is succinct. Discuss if need be. Keegan talk 21:25, 30 January 2009 (UTC)


 * The revision is unacceptable, because by saying "an" instead of "the" it implies there are other calendars with a comparable degree of international acceptance. This is false, and misrepresents the information in the citation. --Gerry Ashton (talk) 21:49, 30 January 2009 (UTC)


 * Hey Gerry. What I find to be disconcerning is not so much the language, but the quotation marks.  MOS guidelines highly discourage this for good reason; it is not encyclopedic language.  I'd like to work with you in constructing a nice first sentence.  The "an" v. "the" argument is pushing around semantics and doesn't really help what I was trying to fix with the presentation of the article.  I agree with you in theory, and disagree in methodology and language.  I saw through the history before I edited the article that you contributed greatly to the subject so if you can provide something more constructive than "unacceptable," I'd be more than happy to listen/read.  If not, s'okay as I have no vested interest in the subject other than maintenance of the project.  Happy editing to you.   Keegan talk 04:24, 31 January 2009 (UTC)


 * I agree that a quote in the first sentence isn't that attractive. The problem is that since many calendars in use in the last few centuries are connected to religion, almost any statement that favors one calendar over another tends to attract spurious edits, so such a statement must be based on a very reliable source if it is to be maintainable. Your statement that "The 'an' v. 'the' argument is pushing around semantics" illustrates the point: if it isn't a direct quote from a reliable source, people will insist on either watering it down to avoid stating the obvious (their favored calendar isn't the standard for international communication and commerce). Or, if the Gregorian calendar is their favored calendar, they will bolster the statement beyond what can be supported by reliable sources.


 * From a style point of view, I'd like to see a close paraphrase of a reliable source, but I think the lack of quotation marks will just invite maintenance problems.


 * I think what can be supported from the sources I've seen is
 * The Gregorian calendar is the predominant calendar in international trade and communication
 * It is the predominant calendar in daily life in a number of areas, such as the Americas and western Europe.


 * I don't know to what extent it is used in daily life in other areas. --Gerry Ashton (talk) 04:41, 31 January 2009 (UTC)


 * Thanks for the swift and thoughtful reply. Everything in the first part makes sense, and to the second part I really like option 1.  "The Gregorian calendar is the predominant calendar in international trade and communication" is succinct in your correct analysis of leaving out a trace of religion to avoid conflict.  It lacks any POV of preference in personal life and religion; it is a fact rather than truth.  I'll take it, but wait a bit to see if or when others chime in.  Two makes consensus naught.  I'll check back in a day or two to see what has developed.  Happy editing to you.   Keegan talk 05:20, 31 January 2009 (UTC)


 * I agree with option 1. I would extend option 2 to include sub-Saharan Africa, Australia/Oceana, and Asia except south Asia from Burma west, areas where the Bhuddist, Hindu, and Islamic calendars are used more in daily life. I include within the umbrella of the Gregorian calendar the calendars of China, Korea, and Japan which number the months instead of naming them and those of Thailand and Japan which don't use the Anno Domini/Common era to number the years. Whether we want to include such a detailed list or any list is open for discussion. — Joe Kress (talk) 22:39, 31 January 2009 (UTC)

Gregorian calendar
I looked everywhere for a wiki Gregorian 2009 calendar. Not being able to find one, I created one myself, found below. I hope others find it helpful:

Ikip (talk) 03:51, 21 February 2009 (UTC)

Errors in "Beginning of year" section?
Back in 2007, I changed the entry for Denmark in the "Beginning of year" section to state that the year started on 1 January since the early 14th century. During the autumn of 2007 someone changed it to its present contents, giving the date as 1559 and adding a comment that there is a difference between when the year number was incremented and when New Year was celebrated.

I have big problems with this entry; in fact, I do not believe it to be true. But before I change anything, I would like to discuss it here.

In the Danish book "Kronologi" by Herluf Nielsen (published by the Danish Historical Society in 1962, 1967, and 1974) there is a long chapter on the beginning of the year. The author's conclusion about new year in Denmark is this (my translation and my comments in square brackets):

"Based on the above facts, one has to conclude that the beginning of the year definitely was 1 January from around 1250, possibly even earlier. However, as the two examples from Lund indicate, it cannot be determined if the year was different in the 11th, 12th and the first half of the 13th century. Only after 1470 did the Royal Chancellery appear to use 25 December as the beginning of the year. This may be because of influence from the south, as a number of the examples from 1473 were issued by Gottorp [a castle in southern Denmark] and concern the internal affairs of the duchies [i.e. southern Denmark, now northern Germany]. ... However, there are no similar examples in private and ecclesiastical letters. Furthermore, one can prove a certain vacillation between 25 December and 1 January in notes by king Frederik I [who reigned 1523-33]. ... In the letter books from the chancellery the year started on 25 December until 1596."

Based on this I make a few observations: Firstly, there is no mention at all of the year 1559 given in Wikipedia. Secondly, there is no mention at all about a difference between the first day of the year and the day on which the year number was incremented. Thirdly (and most importantly), there seems to have been a huge amount of confusion about when the new year should start, and therefore it is a mistake to point to a single year as the turning point. (And this also makes my previous claim about the 14th century too simplistic.) Finally, since even official documents differ on the subject, there appears to have been no official decree determining when the year should begin.

So, I am pretty sure that it is a mistake to list Denmark as changing in 1559. Furthermore, it is a mistake even to give a specific year; more accurately one should write "gradual change between the 13th and 16th centuries".

This leads me to the assumption that a similar uncertainty exists for several of the other countries mentioned. I therefore think a considerable rewriting of the Wikipedia entry is in order. For many countries, the very precise dates should be removed and replaced by more vague (but also more truthful) statements about gradual change. --Oz1cz (talk) 10:58, 28 February 2009 (UTC)


 * Thanks for the additional information. I originally demoted your source because it was not clear whether it referred to the numbered year. But you've convinced me, so please update the entry, including one or both sources at your discretion. The year 1559 can be traced to Handy-book of rules and tables for verifying dates with the Christian era by John J. Bond (1875). Because at least two other years (Roman Catholic Netherlands and Russia) given by Bond are known to be in error, his entire list is in doubt. Although both internet sources given at the head of the column appear to be derived from Bond, they have condensed the information given by Bond, including the removal of some 'gradual change' indicated by Bond himself for many countries, including Denmark. Unfortunately, no other list of the commencement of the year (as opposed to adoption of the Gregorian calendar) appears to be available. Bond apparently used government sources in London. — Joe Kress (talk) 16:39, 2 March 2009 (UTC)


 * Okay, I've made some rather drastic removals from the table (and also made a small addition about Russia in 1492). Because of the uncertainty of the dates, I believe that we should not have anything in there that is not specifically supported by a reference. If I have been to harsh, please feel free to add back some of the content I have removed. --Oz1cz (talk) 07:50, 3 March 2009 (UTC)


 * It would be helpful to include page numbers from references. Also, Blackburn & Holford Strevens is already listed in the bibliography, so a short footnote would be OK. --Gerry Ashton (talk) 12:34, 3 March 2009 (UTC)


 * Done. --Oz1cz (talk) 15:48, 3 March 2009 (UTC)


 * Your change was too drastic so I've recovered the dates. We should not throw the baby out with the bath water. Although the ultimate source of the list may be Bond, the proximate source was a list identical to the Internet versions which has appeared in Whitaker's Almanac for many years. I believe we should accept dates from a source like Bond or Whitaker's unless proven wrong. Just because Denmark was gradual does not mean that most countries were. I know for certain that France adopted 1 January in 1564 by decree because I have a copy of the decree, yet the change was also gradual because the decree did not specify a date certain, so some departments (French states) changed as soon as the decree was issued while others, like Paris itself, did not change until later in the year or even early the next year. I'll add that source and another for Russia which gives an English translation of the decree of Peter the Great. Portugal changed on the date given because several other sources give that year. I suspect that Hermann Grotefend (the Southern Netherlands source) has many more. — Joe Kress (talk) 01:27, 4 March 2009 (UTC)


 * That's fine, Joe. I just wonder if we really should include the reference to История календаря в России и в СССР (Calendar history in Russia and the USSR) since that page, as far as I can tell, is merely a verbatim copy of Seleschnikow's book. Also, I don't see that web page crediting Seleschnikow (Селешников) as the source. However, being a web page, it is, of course, more easily available than a printed book.--Oz1cz (talk) 14:09, 7 March 2009 (UTC)


 * I decided to merge the two Seleschnikow references--Oz1cz (talk) 14:17, 7 March 2009 (UTC).


 * Wow, we both give the same Russian source without realizing it. I now see that the home page of Anatoly Grigorenko does state that he presents "the electronic version of the book" История календаря и хронология by Селешникова (History of the calendar and chronology by Seleshnikova). — Joe Kress (talk) 06:51, 8 March 2009 (UTC)

Skip six days?
This passage was just added by an I.P. editor: Is is known that till the year 10,000 there must be skipped six days, otherwhise the vernal equinox will fall in that year on 15 March instead of 21 March. It is also known that around the year 4000 only one day must be skipped and till about 6000 an other day must be skipped and since after about the year 7200 the vernal tropical year (Jean Meeus calls this the E-E year in his "More Mathematical Astronomy Morsels" (Morsels II)) will be quickly shorten, four additional days must then be skipped! This can be done very well by changing the six century leap years 4000, 6000, 7200, 8400, 9200 and 10,000 all into common years.

I find this impossible to believe, because the Gregorian calendar uses actual solar days, and the gradual slowing in the rotation of the earth is not predictable enough to make the above statement. --Gerry Ashton (talk) 16:02, 2 March 2009 (UTC)


 * Meeus (p.363) gives a table of the date of the vernal equinox from 2000 to 8000 every 400 years (the Gregorian cycle) in both uniform Dynamical Time and variable Universal Time. In DT the date changes slightly from March 20.310 to March 20.053 or 0.257 days in 6000 years. In UT it changes from March 20.308 to March 18.926, 1.382 days in 6000 years, which is the limit of the equations he used given by Simon et al. in "Numerical expressions ...". UT was obtained from DT by subtracting ΔT=102+102t+25.3t² seconds where t is in Julian centuries since 2000 recommended by Chapront and Francou in 1997, which gives 1.126 days in 60 centuries, in agreement with the table of Meeus. This is a bit smaller than the value derived by F. R. Stephenson from 2700 years of solar eclipses (−20+32((1820−Year)/100)² s). The latter would add 1.414 days in the year 8000 for a total change to 1.671 days.


 * Anonymous wrongly interpreted a discussion by Meeus two pages earlier. Meeus derived six days of Universal Time after 10000 years in the year 12000, not in the year 10000, only 8000 years in the future. This value was for the mean tropical year, not the vernal equinox year. Chapront and Francou's ΔT was originally specified for the period +948 to +1600. In an earlier paper Stephenson derived 1.7 ms/cy consisting of a lunar tidal acceleration of 2.3 ms/cy (constant if sea level does not change) reduced by a mean post glacial uplift of 0.6 ms/cy over 2700 years. However, the uplift is not constant, but has a relaxation constant of a few thousand years, maybe 10000, the value is uncertain. At the end of 10000 years it would be substantially lower, possibly doubling the coefficient of t². Of course, the predicted global warming will probably melt the Greenland and West Antarctic ice sheets in only 1000 years. This has several complex interactions, including a much higher sea level and a drastic increase in post glacial uplift, with unknown consequences for ΔT. — Joe Kress (talk) 22:39, 2 March 2009 (UTC)


 * Lest this be misunderstood, Meeus does not advocate any modification of the Gregorian calendar, as Anonymous did.
 * We see that, even by considering the slowing down of the Earth's rotation, the Gregorian calendar will not be more than 1 day off [relative to the vernal equinox year] (as compared to the year 2000) until about A.D. 7200. Later, however, the situation will deteriorate considerably. ... The conclusion is evident: we cannot invent calendar rules valid for tens of thousands of years into the future — nor is there a need to do so. [Jean Meeus, More mathematical astronomy morsels, page 264]
 * — Joe Kress (talk) 19:17, 3 March 2009 (UTC)
 * citation must be wrong: all "more ... morsels" books by page 264 deal with planets, not calendars. Tom Peters (talk) 13:00, 9 March 2009 (UTC)


 * Sorry for the typo—the page was 364. — Joe Kress (talk) 18:03, 9 March 2009 (UTC)

Unsourced proposal description
This passage was added to the article: If the years 3200, 6400, 9600, 12,800, 16,000 and so on are NOT leap years the duration of the mean Gregorian year will then be 365.2421875 days (10,000 devided by 3200 gives 3.125) and this approaches very close the real duration of the mean tropical year which lasts 365.24219 days. So that a very little error of only 3.125 - 3.100 = 0.025 days in 10,000 years will then be made.

I have moved it here for two reasons. First, it is unsourced. Second, since the Gregorian calendar uses actual solar days, not days of exactly 8600 SI seconds, I don't believe it is possible what the ideal number of leap-days would be so far in the future. --Gerry Ashton (talk) 18:06, 26 February 2009 (UTC)

Gerry, you DO mean 86400 SI seconds instead of 8600, don't you? Glenn L (talk) 05:16, 13 April 2009 (UTC)


 * Three centurial year corrections to the Gregorian calendar were proposed before the variability of the year and day were known: dropping a leap day every 3600 years by Delambre, every 4000 years by John Herschel (see Butcher), and every 3200 years by Madler (see tropical year). The last produces the same average length of 365.2421875 days as dropping an additional leap day from the Julian calendar every 128 years, proposed by Madler and Butcher. — Joe Kress (talk) 08:48, 27 February 2009 (UTC)

Suppression of CE, BCE notation
In [Unsigned comment by 68.154.253.60 this edit] the anonymous editor using IP address 68.154.253.60 has suppressed the notation Common Era, CE, Before the Common Era, and BCE. His reason for doing so is that "No citation has been provided that the decree from Pope Gregory included BCE and CE as an alternative to BC and AD." This is patent nonsense, because anyone with an ounce of sense (or who reads the bull, which is cited) knows the bull was not written in English and would not contain any English language nomenclature for the era. The introduction contained an appropriate degree of complexity as it stood before the change. If desired, a section could be added explaining that the bull did not specifically address the year numbering system or the name for that system, but did implicitly endorse it by using it to specify when the decree was signed, when it would go into effect, and specifying some of the years that would be leap years. The decree only mentions the name of the year numbering system once, at the end, where the bull was signed. It used the term "anno Incarnationis dominicæ". --Jc3s5h (talk) 00:11, 26 March 2009 (UTC)


 * It cannot be argued that even in Latin that the Pope intended BCE and CE to be alternatives. I have no objection to a section, which I have already created, that states that these alternatives have been created over time.  However, I strongly object to any attempt to go back in time and change history.  The Pope was not worried about offending non-Christian with the use of BC or AD.  This is something that took place long after the decree, and that distinction needs to be perfectly clear.  This is far from "nonsense."  This is based in logic which is: we must separate the origins of the calendar and the political correctness which has taken place since its creation. We cannot allow for this to be blended together leaving people to believe the decree from Pope Gregory XIII included BC/BCE - AD/CE.68.154.253.60 (talk)
 * That's bull and you know it. —Preceding unsigned comment added by 67.53.37.221 (talk) 05:40, 31 March 2009 (UTC)

Oriental Orthodox
The information about the Oriental Orthodox and their acceptance/non-acceptance of the Gregorian Calendar is not entirely true. For one thing, the Armenian Apostolic Church, including the Catholicosate of Etchmiadzin and the Catholicosate of Cilicia both have adopted the Gregorian Calendar. The only exception within the Armenian church is within the small population within "the Holy Land". The Oriental Orthodox in India have also adopted the Gregorian calendar. This includes the "autocephalous" Malankara Orthodox Syrian Church and even also the Malankara Archdiocese of the Syriac Orthodox Church. I would like to thus correct the information on the Orientals. Deusveritasest (talk) 06:31, 18 April 2009 (UTC)


 * Please correct the section. — Joe Kress (talk) 03:28, 20 April 2009 (UTC)

Adoption in Sweden
In the account of the adoption of the Gregorian calendar in Sweden the year 1700 is alleged to be a leap year. To my understanding this is not correct. Did the Swedes get it wrong or is the account of the adoption wrong or am I wrong? Pietvanzon (talk) 15:57, 16 May 2009 (UTC) Piet van Zon


 * I see nothing wrong with the article's description of Sweden's adoption, but its wording could be improved if you misunderstood it. The intent was to gradually transistion from the Julian to Gregorian calendars over forty years by dropping all 11 leap days within the period 1700 to 1740. But the leap days in 1704 and 1708 were not dropped because the Great Northern War diverted Sweden's attention. Thus 1700 was not a leap year. — Joe Kress (talk) 21:36, 16 May 2009 (UTC)

Need clarification
See leap year, and they say the error amounts to one day in 8000 years, not 3300 years as stated here. Which is correct?--61.200.144.117 (talk) 02:45, 29 May 2009 (UTC)


 * They are both right, but long-term predictions are futile. If we compare the Gregorian calendar rules to the present mean vernal equinox tropical year, we get an error of 1 day in about 8,000 years. If we compare to the mean tropical year (which, roughly speaking, is an average of every possible starting date for the year, not just the vernal equinox) we get an error of 1 day in about 3,300 years. But both kinds of tropical years are changing length (as measured by atomic clocks). Furthermore, the length of the real solar day is getting longer (as measured by atomic clocks), and is unpredictable. Calendars, of course, count real solar days, not some abstract day measured in time laboratories. Thus, even if we wanted to reform the calendar, we can't predict the length of future years well enough to know if any proposal would be better or worse than the Gregorian calendar over a period of 10,000 years or so. --Jc3s5h (talk) 04:53, 29 May 2009 (UTC)


 * As Jc3s5h notes, both errors consider only the present lengths of these years. If the changing lengths of both years over thousands of years are considered, then the error becomes quite complicated. Solar year range by Irv Bromberg plots these variable years over thousands of years. The average Gregorian calendar year would be a horizontal line 49:12 in excess of 365d 5h. See The lengths of the seasons for an explanation of these plots. Note that the vernal equinox year (green) is relatively constant near 49:00 only for 2000 years into the future, yielding an error of 0.28 days at the end of that period. The noticable downward slant for all years is caused by the Moon's tidal friction on Earth which lengthens all solar days, hence reducing the number of days in each year.


 * The area between the horizontal Gregorian line and the curved line of the selected tropical year is its error. An error of 1 day corresponds to an area of 1 day. This area is below the Gregorian line, to the right of the year 2000, and above the tropical year. The right-hand year is selected so that the enclosed area is 1 day. The difference between the future year and 2000 is the number of years needed to accumulate an error of 1 day. A rough estimate can be obtained by counting the plot's rectangles, noting that each rectangle is about $$ \tfrac{2600\text{yr}\times 15\text{s/yr}}{3600\text{s/h}\times 24\text{h/d}} $$ or 0.45 days. Much more precise values can be obtained by printing the plot on graph paper with much smaller squares and counting them. Even better would be a planimeter. These plots were obtained using numerical integration, so analytical equations suitable for electronic calculators are not available, although they could be generated by a curve fitting program. Using small squares an error of 1 day relative to the vernal equinox year (green) will be reached at about the year 7000 or 5000 years from now. Conversely, an error of 1 day relative to the mean tropical year (black) will be reached at about the year 4200 or only 2200 years from now. -- Joe Kress (talk) 00:34, 30 May 2009 (UTC)

Juche Calendar
The article states, "Korea started using the Gregorian calendar on 1 January 1896 owing to Japanese influence. The lunisolar Korean calendar used immediately before that day was based on the lunisolar Chinese calendar." Since 1997 the North Koreans have not used the Gregorian calendar, rather they have instituted the Juche Calendar. Making sweeping generalisations about "Korea" simply won't work since there are two nations that use that name. Note the following press release from KCNA:


 * Pyongyang, May 22, 1998 (KCNA) -- The Juche calendar is used in Korea as a new chronological notation. The use of the newly instituted Juche calendar from 1997 is a great event in the 5,000-year history of Korean nation. It is a revolutionary calendar fundamentally different from the old calendars in content, nature and usage. Recorded in the Korean history were the Yongrak calendar (long blessings) used by King Kwanggaetho of Koguryo (391-412) for 22 years, the Chonsu calendar (meaning that the heaven gave royal authority) utilized by King Wanggon, the founder of Koryo, the first unified state, for 12 years from 918 to 929 and Kwangmu calendar (meaning to shed lights with might) used by King Kojong for 11 years from 1897 to 1907 in the modern history. And some of the kings of Koguryo, Paekje and Balhae used their calendars. The old calendars reflected subjective desires of the rulers. However, the social conditions of those years were contrary to "good meaning" of calendars, and the period of their use was very short. In the Juche calendar, 1912 when President Kim Il Sung was born is the first year (Juche 1). It symbolizes his glorious and brilliant revolutionary history and exploits. Consistent with the great idea, theory, method and virtues, Juche is a cornerstone which represents the life and exploits of the President. Accordingly, it contains his brilliant life and great exploits and ethics and aspirations of the new era. Also reflected in it are the unanimous desire and aspirations of all the Korean people to make their country liberated and developed by the President shine as Kim Il Sung's Korea and his history continue in the country. The epoch-making change in the life and destiny of the Korean people was unthinkable without his august name. So, people across the country including veteran party members of a forestry workers' village in Unhung county, Ryanggang Province, in their letters to the Central Committee of the Workers' Party of Korea, wrote that the age of Korea must be counted from 1912 and the genuine history of Korea must be recorded from it. The Juche calendar is an eternal one of Kim Il Sung's nation, which will be used for all ages together with the history of Korea. —Preceding unsigned comment added by 66.220.193.142 (talk) 18:28, 29 May 2009 (UTC)


 * Only one Korea existed before 1945, which used the Gregorian calendar since 1895, using year numbers which were usually not Western years (see Korean calendar). Since 1945 both Koreas have continued to use the Gregorian calendar for their days and months, but have often used different year numbers. In other words, "Gregorian calendar" only describes the method of organizing days into months—it does not apply to year numbers. The Juche calendar used by North Korea since 1997 is the Gregorian calendar with a different numbering system for its years than the numbering system used by South Korea and the West. All Juche calendar days and months are identical to the South Korean calendar and to the Gregorian calendar. Thus month 1 (January) begins on the same day in both North Korea and in South Korea, as do all other days of the year. Even the leap day, day 29 of month 2 is on the same day in both calendars. — Joe Kress (talk) 21:55, 29 May 2009 (UTC)

Introduction
The Introduction has : "decreed by Pope Gregory XIII, after whom it was named, on 24 February 1582 by the papal bull Inter gravissimas."

That's simplified too much. It was there, at the time, still 1581. "Datum Tusculi Anno Incarnationis Dominic&aelig; M. D. LXXXI. Sexto Calend. Martij, Pontificatus".

It would seem appropriate to give the local date, the Julian date, and the Gregorian date.

In those days, it seems, Popes worked on Saturdays.

82.163.24.100 (talk) 21:20, 13 June 2009 (UTC)

Second paragraph has : "the de facto international standard". It is de jure, and ISO 8601 should be cited. 82.163.24.100 (talk) 21:24, 13 June 2009 (UTC)

General : (a) In the change, no days were skipped. Ten or so dates were skipped. (b) Leap Seconds scarcely belongs; but it should not share a section title with date material. It should be in its own subsubsection, if at all. 82.163.24.100 (talk) 21:34, 13 June 2009 (UTC)


 * As for the date in Rome when the decree was signed, the variations in the beginning of the year are discussed in the Beginning of the year section. The introduction is intended to give a simplified overview; obscure details do not belong in the introduction.


 * "De jure" means according to law. There are hundreds of countries, and some of those countries may leave calendar matters to provinces, states, or the like, so there may be a thousand jurisdictions that would have to be investigated to discover the extent to which the Gregorian calendar is the de jure calendar. Get back to us when you're done. Hope you survive investigating in some of the failed states.


 * The point about skipping dates, not days, does have some value. Perhaps we should rephrase the sentences that contain the word "skip". --Jc3s5h (talk) 23:36, 13 June 2009 (UTC)


 * Four different dating clauses are given in the papal bull at Inter gravissimas. Two use a four digit year, 24 February 1581 when the bull was signed used the incarnation year, and 1 March 1582 when the bull was printed used the nativity year. All four years agree that the bull was signed 24 February 1582 for our modern year beginning 1 January. I agree with Jc3s5h that the simplified date that is now in the introduction is sufficient. I agree with Anonymous (82.163.24.100) that leap seconds do not belong in the article because the calendar uses variable mean solar days, not uniform atomic days. — Joe Kress (talk) 07:20, 14 June 2009 (UTC)

Accurracy
I noticed that the Accuracy section shows a graph that shows the Year 2000 as being no leap. The Year 2000 is divisable by 400 and therefore should be a leap year. This graph, therefore, requires re-working. Possibly to show the years around 2100 rather than year 2000. NightKhaos (talk) 15:43, 29 June 2009 (UTC)
 * It appears I misunderstood the graph. Nevermind. NightKhaos (talk) 15:45, 29 June 2009 (UTC)

Table of Differences between Gregorian and Julian calendar dates
I saw someone attempt to correct and error in the table of differences between Gregorian and Calendar dates. I realised that the error arose because some days have an ambiguous difference between their Gregorian and Julian calendar dates. I became aware of such ambiguous days, when someone attempted to write a calendar conversion program based on such a table of difference and got incorrect results for such ambiguous days. Therefore I decided to exclude such days from the table.

I give an example of such a day. The day that the Gregorian Calendar calls March 4, 1900 and the Julian Calendar calls February 20, 1900. Now what is the difference? It depends on how many days there are in February. If February has 28 days, the difference is 12 days, if February has 29 days it is 13 days. How many days does February have? It depends on the calendar. Hence the difference is not well defined. Karl (talk) 10:52, 9 July 2009 (UTC)


 * There is no ambiguity in calendar conversion. A 1-to-1 mapping can be performed between Gregorian and Julian dates. This indicates that the structure of the table is flawed. We should try to find a table with a better structure, or better usage instructions. --Jc3s5h (talk) 11:43, 9 July 2009 (UTC)


 * Yes a 1-1 mapping can be performed between Gregorian and Julian dates, but such a mapping cannot rely on a simple notion of a difference between two dates. One could put in a more complicated table to account for this, but I am not sure that this article is a really good place for it. Karl (talk) 12:10, 9 July 2009 (UTC)


 * Whether a more complicated table is appropriate depends on how elegant the new table is. I guess we can't decide until someone finds a promising table to suggest. --Jc3s5h (talk) 12:16, 9 July 2009 (UTC)


 * One could always put such a table in this talk section to be commented upon. Karl (talk) 12:21, 9 July 2009 (UTC)

The table could be expanded thus (only end part shown): but I'm not sure whether it is worth the complication just to cater for a few more days. Karl (talk) 14:35, 31 July 2009 (UTC)


 * Unfortunately, vandals like to change numbers, and those cleaning up after the vandals may not have the skills to reconstruct tables. Thus, it would be better if the table were taken directly from some reliable source, rather than requiring any reasoning on the part of Wikipedia editors. --Jc3s5h (talk) 17:21, 31 July 2009 (UTC)

Unsuitable wording
"The Gregorian calendar modifies the Julian calendar's regular four-year cycle of leap years as follows: ..." (what follows describes the Gregorian formula, but does not say anything about the Julian formula). So it's not saying how the Gregorial calendar modifies the Julian. Odd wording, and not quite correct.

" Thus, the essential ongoing differentiating feature of the Gregorian calendar, as opposed to the Julian calendar, is that the Gregorian omits 3 leap days every 400 years. This difference ..." Once again, odd and not quite correct wording. The Gregorian calendar is described, but the "difference" between the Julian and Gregorian calendars is not mentioned.

It reads like a 10th-grade report, not an encyclopedia. —Preceding unsigned comment added by 4.154.229.145 (talk) 00:59, 15 October 2009 (UTC)


 * The portion you quoted already states the Julian formula as a "regular four-year cycle of leap years", which was clarified in the first phrase of the following quote as those years "exactly divisible by four". That means that all centurial years are leap years in the Julian calendar. I'm clarifying those sections. — Joe Kress (talk) 03:05, 15 October 2009 (UTC)

Edit war over "Christ"
I find this rather confusing. One party is not ok with referring to Jesus as Jesus Christ. Yet you seem perfectly fine with the article referring to him as having been incarnate. How is that any less POV than referring to him as a Christ? If anything, I would think it would be more POV. Deusveritasest (talk) 20:24, 19 October 2009 (UTC)


 * I cannot fully answer your question without seeing the exact context. Please provide a phrase I can search for so I can find where the article mentions "incarnate". Per American Heritage Dictionary 3rd ed. the first definition of incarnate is "Invested with bodily nature and form; an incarnate spirit". So the word incarnate does seem to imply a belief that people have a soul or spirit. That should be marked in some way as a religious belief.


 * If the belief is true, then Jesus is not unique; every human being is incarnate, so Jesus is not being singled out.


 * Also, it is important to use the term "incarnation" because that is what Dionysius Exiguus used. The meaning of the epoch of the year numbering system used throughout the world cannot be fully understood if some other word is used. --Jc3s5h (talk) 20:59, 19 October 2009 (UTC)


 * It's in the header in this sentence: "Gregory's bull does not ordain any particular year-numbering system, but uses the Anno Domini system which counts years from the traditional Incarnation of Jesus, and which had spread throughout Europe during the Middle Ages." This seems to be indicating an event and does it in such a way that is not representing belief but rather is simply taking it for granted as that something that actually happened.


 * Let me point out that referring to Jesus as incarnate typically is not simply attempting to speak of him possessing flesh, but rather is an indication of the belief that he was a spirit that, in some form or another, preceded his fleshly form and later came to possess it in the event called "the Incarnation". That is clearly an even more religious belief even beyond the simple idea that he was a fleshly being who had a soul, and it does set him apart from the rest of humans. Typically, for those who refer to this incarnation, it is not believed that other humans preceded their flesh. Deusveritasest (talk) 06:53, 20 October 2009 (UTC)


 * OK. I notice that the phrase is "traditional Incarnation of Jesus". I think the word "traditional" does double duty; Wikipedia is presenting it as a tradition, and neither claiming there was an actual Incarnation, nor that the Incarnation actually occurred in the year BC 1 or AD 1. Keeping in mind that the lead section should be concise, can you think of a way to word it better, while retaining the word "Incarnation" (or "incarnation")?


 * The word is important because it is a point of controversy. Pro-life activists consider incarnation to occur at conception, and use that argument to oppose abortion and artificial contraception. Pro-choice activists don't always accept the concept of incarnation at all, or don't accept that it occurs at conception. In ancient times, the distinction concerning whether incarnation occurred at birth or conception was not clearly drawn, and we don't know what Dionysius Exiguus had in mind, so that adds more uncertainty concerning when the Anno Domini era was intended to begin. --Jc3s5h (talk) 15:34, 20 October 2009 (UTC)

Counter-Reformation
I edited this:

“Many non-Catholic countries initially objected to adopting a Catholic invention, despite the efforts of the Counter-Reformation (of which Gregory was a leading proponent); some Protestants feared the new calendar was part of a plot to return them to the Catholic fold"

I changed “despite” to “due to”, as

The present version suggests the Counter-Reformation would serve to overcome the objections of Protestants, wheras if anything it would be more likely to create such objections, particularly to an innovation by Gregory, one of CRs leading proponents.

The change was reverted; would anyone like to explain why?Moonraker12 (talk) 12:32, 27 October 2009 (UTC)


 * I have not read the source. I assume good faith and suppose that the editor who put that in fairly reflected the source. Neither of us should change it unless we read the source, or delete the citation. The Counter-Reformation tried to correct some of the complaints that Protestants had with the Catholic church, while standing fast on other complaints. Perhaps the author of the source determined that at the point the Gregorian calendar was being adopted, the responses to Protestant complaints had a chance of persuading the Protestants to adopt the calendar. --Jc3s5h (talk) 16:57, 27 October 2009 (UTC)

I have copied the source (Gordon Moyer, May 1982, "The Gregorian Calendar", Scientific American, p. 144). The relevant paragraph states

The controversy was as much religious as it was academic. This was the age of Reformation; Protestant countries rejected the new calendar, denouncing it as a papal scheme to bring their rebellious fold back under the jurisdiction of Rome. The accusation was not entirely unfounded. Gregory XIII was a vigorous&mdash;in fact, a ruthless&mdash;promoter of the Counter Reformation. He assisted Philip II of Spain in his scourging of the Protestant Dutch and gleefully accepted the head of the leader of the French Huguenots after the infamous St. Bartholomew's Day Massacre, a blood bath that the pope celebrated as a Catholic victory, ordering a special medal struck in its commemoration. Gregory Probably saw it as an opportune time to impose a calendar reform on the Christian world, which he did by threatening to excommunicate anyone who refused to accept it.

I have edited the article to more closely reflect the source. --Jc3s5h (talk) 21:12, 27 October 2009 (UTC)


 * I take your point about editing a sourced statement; I hadn’t thought that bit through. Your edit to the article looks fine. Moonraker12 (talk) 12:51, 30 October 2009 (UTC)

Western calendrical science
[Adoption in Eastern Asia] needs to be cleaned up, as it misleads as to when these cultures began to utilize Western calendrical science. China and Korea were aware of and utilizing Western calendrical science from the 17th Century. This section is stereotypical within the context of East Asian Studies in its representation of Japan as "first". The Korea section has been updated with an academic reference, but the Japanese and Chinese sections have not. —Preceding unsigned comment added by Mindlessbuddha (talk • contribs) 13:56, 22 November 2009


 * Some clarification is needed. "Western calendrical science" doesn't mean the Gregorian calendar—it means Western astronomy brought to China by Jesuit missionaries during the last years of the Ming Dynasty (beginning in 1601). In China, astronomy's primary purpose was to calculate the calendar, so its astronomical knowledge was called "calendrical science". Western tables of the Sun and Moon were adapted to the meridian of Beijing and used to calculate the beginning of each lunar month in the traditional Chinese calendar and to determine when its intercalary month should be added. These tables were translated into Chinese during the period 1629–1635 under the direction of Xü Guanqi, the director of the emperor's Bureau of Astronomy, but they were not officially adopted by China until 1645, shortly after the Qing Dynasty conquered the country. Of course this section can be expanded in this manner, but that has nothing to do with the Gregorian calendar which is the subject of this article, so it has not been added. — Joe Kress (talk) 19:21, 22 November 2009 (UTC)


 * I cannot justify the addition of Korean "western calendrical science", actually Western astronomy, which has nothing whatsoever to do with the Gregorian calendar, the subject of this article, so I am removing it. This misconception was caused by the unfortunate use of "Western calendar" for a section discussing Western astronomy in books by Robert H. Lee and others. For example, Sourcebook of Korean Civilization: Vol.2: From the seventeenth century to the Modern Period edited by Peter H. Lee, pp. 110–114. This same book states that Yu Kilchun actively participated in implementing the Gregorian calendar during the 1894–95 reform movement (p. 341), which I am adding to the article. — Joe Kress (talk) 06:54, 27 December 2009 (UTC)

Role of explanatory words
Edit summary for edit by Dan Hartas reads: "All papal bulls are known by their opening words, no need to make specific reference to it." (And he reverts on that explanation.) Clearly Dan Hartas knows this, but I suggest that the question should rather be, what is helpful to a reader of the encyclopedia? Does the average reader know this? It is arguably not so relevant whether Dan Hartas, or I, or any other individual editor knows it. Terry0051 (talk) 19:23, 2 December 2009 (UTC)


 * I agree that the explanation belongs in the article, because Wikipedia should be written for readers (who don't know the subject), not for editors (who do know the subject). — Joe Kress (talk) 21:33, 2 December 2009 (UTC)

I am just an average person and not Catholic. I had to do research when I got to the part about a "bull" that talks or has special ordaining powers. "Gregory's ""bull"" does not ordain any particular year-numbering system..". There needs to be reference to papal bull to clarafy this. —Preceding unsigned comment added by Otr500 (talk • contribs) 15:09, 17 December 2009 (UTC)

I see from my post I am still learning. Without objections this will provide a solution bull. Otr500 (talk) 15:23, 17 December 2009 (UTC)


 * The words 'papal bull' are already wikilinked --- in the very first paragraph. So a reader who wants information about this expression can already go by the link to the relevant article. (Maybe Otr500 didn't see the first paragraph and didn't notice this?)  The WP guidelines discourage undue multiplication of the same wikilink (See WP:Link). Terry0051 (talk) 15:33, 17 December 2009 (UTC)


 * I reverted the second link. — Joe Kress (talk) 03:32, 18 December 2009 (UTC)

You are right I read it and missed the link. Thanks, Otr500 (talk) 08:19, 18 December 2009 (UTC)

Number of leap years starting on a given day of the week
Although the number of leap years per cycles is stated at 97, the allocation to how many started on which day of the week adds up to 98. Huh?

I've reproduced this a couple of ways and so am now confident that the correct information is: Sun, Mon, Tu, ..., Sat respectively 15, 13, 14, 14, 13, 15, 13. So, the only issue was with Wednesday which was stated at 15 and should be 14. I'll correct the main page to so indicate.

The sequence is also symmetrical as I'd expect. It is symmetical about leap years starting on Saturday. The year 2000 is such a year and the arrangement of Gregorian leap years is symmetrical about that year. Karl 20 Oct 2005


 * Do you have a reference for how the distribution of day of week was calculated? I am curious to see your method since I ran my own program (http://python.pastebin.com/f4c091a5e) and got a different distribution. I would offer up my program as "proof", but in keeping with Wikipedia neutrality standards of no original research, a link to a third-party source describing how to calculate the frequency would probably be best? Presto8 (talk) 06:44, 18 January 2010 (UTC)


 * Never mind, I figured it out. One set of data is showing the day of week that the leap year starts, the other set of data is showing the day of week that the leap day occurs. I'm going to add this extra information to make it more clear since I think it's pretty easy to mistake it the way it was. Presto8 (talk) 21:18, 19 January 2010 (UTC)

Recent IP edits
There have been a series of edits by 156.61.160.1 (talk) and 62.31.226.77 (talk) which revert to some old version of the page. I find the edit summaries indecipherable, but this editor will not use the talk page. It is essential that either these edits stop or an explanation be provided here. --Jc3s5h (talk) 14:44, 21 January 2010 (UTC)


 * Yes, I agree those IP-originating edits need at least some good explanation, they don't look constructive. Terry0051 (talk) 15:31, 21 January 2010 (UTC)

Novel conversion procedure
The novel conversion procedure introduced in this edit by 62.31.226.77 is being discussed at No original research/Noticeboard. Jc3s5h (talk) 21:09, 12 February 2010 (UTC)


 * The novel conversion procedure is wrong. A few examples suggests it might actually give the difference of dates in the Julian calendar and New Calendar a.k.a. Revised Julian Calendar. First consider the year 1200, which is evenly divisible by 400, so is a leap year in the Gregorian calendar. Since every centurial year is a leap year in the Julian calendar, the difference should not change between 1199 and 2000.


 * However, when 1200 is divided by 900, it leaves a remainder of 300. Since the remainder is neither 200 or 600, it is not a New Calendar leap year.


 * Using the procedure in the article to compute differences, we find (using integer division)


 * ((1199 + 300) / 100) * 7 / 9 - 4 = 6


 * ((1200 + 300) / 100) * 7 / 9 - 4 = 7


 * So there is an increase in the difference when it should have stayed the same.


 * For the year 2800, when it is divided by 900 the remainder is 100, so it is not a New Calendar leap year, but it is a Gregorian leap year. Like 1200, there should be no change in the Gregorian to Julian difference between 2799 and 2800. Doing the math,


 * ((2799 + 300) / 100) * 7 / 9 - 4 = 19


 * ((2800 + 300) / 100) * 7 / 9 - 4 = 20


 * So the procedure is clearly wrong and should be removed Jc3s5h (talk) 01:44, 16 February 2010 (UTC)

I have reported the reintroduction of the incorrect procedure at WP:ANI. Jc3s5h (talk) 20:30, 16 February 2010 (UTC)


 * The formula given by 156.61.160.1/62.31.226.77 for the number of days that the Gregorian calendar is ahead of the Julian calendar is Trunc{[(H+3)×7/9]−4}, where H is the hundreds digits. The centurial years that the Gregorian calendar (proleptic before 1582) advances by one day over the Julian calendar and the cumulative total for several centuries is (note the 0 1 1 1 blocks):
 * {| class=wikitable


 * - align=right
 * −500||−400||−300||−200||−100||   0||100||200||300||400
 * 500||600||700||800||900||1000||1100||1200||1300||1400
 * 1500||1600||1700||1800||1900||2000||2100
 * - align=right
 * 1||0||1||1||1||0||1||1||1||0
 * 1||1||1||0||1||1||1||0||1||1
 * 1||0||1||1||1||0||1
 * - align=right
 * −5||−5||−4||−3||−2||−2||−1||0||1||1
 * 2||3||4||4||5||6||7||7||8||9
 * 10||10||11||12||13||13||14
 * }
 * The centurial years that the Revised Julian calendar or New calendar (proleptic before 1923) advances by one day over the Julian calendar and the cumulative total for several centuries is (note the 0 1 1 1 0 1 1 1 1 blocks):
 * {| class=wikitable


 * - align=right
 * −500||−400||−300||−200||−100||   0||100||200||300||400
 * 500||600||700||800||900||1000||1100||1200||1300||1400
 * 1500||1600||1700||1800||1900||2000||2100
 * - align=right
 * 1||1||0||1||1||1||1||0||1||1
 * 1||0||1||1||1||1||0||1||1||1
 * 0||1||1||1||1||0||1
 * - align=right
 * −6||−5||−5||−4||−3||−2||−1||−1||0||1
 * 2||2||3||4||5||6||6||7||8||9
 * 9||10||11||12||13||13||14
 * }
 * The result of the formula before truncation and then after substituting floor for truncation to properly handle negative results is:
 * {| class=wikitable


 * - align=right
 * −500||−400||−300||−200||−100||0||100||200||300||400
 * 500||600||700||800||900||1000||1100||1200||1300||1400
 * 1500||1600||1700||1800||1900||2000||2100
 * - align=left
 * −5.55||−4.77||−4.00||−3.22||−2.44||−1.66||−0.88||−0.11||0.66||1.44
 * 2.22||3.00||3.77||4.55||5.33||6.11||6.88||7.66||8.44||9.22
 * 10.00||10.77||11.55||12.33||13.11||13.88||14.66
 * - align=left
 * −6||−5||−4||−4||−3||−2||−1||−1||0||1
 * 2||3||3||4||5||6||6||7||8||9
 * 10||10||11||12||13||13||14
 * }
 * The result differs from the Gregorian calendar minus the Julian calendar, but is quite close to the Revised Julian calendar minus the Julian calendar, differing only where the remainder is an integer. This can be corrected by subtracting 4.05 instead of 4, thus the corrected formula for the number of days that the Revised Julian calendar is ahead of the Julian calendar is Floor{[(H+3)×7/9]−4.05}. Because this does not concern the Gregorian calendar, it does not belong in this article but is appropriate for the Revised Julian calendar article.


 * The corresponding formula for the Gregorian calendar is Floor{[(3/4)×H]−1.25} which yields:
 * {| class=wikitable


 * - align=right
 * −500||−400||−300||−200||−100||0||100||200||300||400
 * 500||600||700||800||900||1000||1100||1200||1300||1400
 * 1500||1600||1700||1800||1900||2000||2100
 * - align=left
 * −5.00||−4.25||−3.50||−2.75||−2.00||−1.25||−0.50||0.25||1.00||1.75
 * 2.50||3.25||4.00||4.75||5.50||6.25||7.00||7.75||8.50||9.25
 * 10.00||10.75||11.50||12.25||13.00||13.75||14.50
 * - align=left
 * −5||−5||−4||−3||−2||−2||−1||0||1||1
 * 2||3||4||4||5||6||7||7||8||9
 * 10||10||11||12||13||13||14
 * }
 * I'm changing the article accordingly. — Joe Kress (talk) 07:58, 18 February 2010 (UTC)

Table by LenderCarl
I removed the most recent perpetual Gregorian calendar table by LenderCarl in wikitable format because it has way too much information for this article. If other editors disagree with me, discuss it here. I do not object to this information in the form of a thumbnail image, because then this massive information is not actually in the article and any reader who needs more information can click on the thumbnail. If kept in wikitable format, it would be appropriate in Wikisource (see Wikisource:Help:Adding texts) with a link within this article. Even though the editor has published this information in other publications, and hence it is not original research, it should not be reprinted here. Wikipedia is an encyclopedia, a tertiary source, which summarizes secondary sources, it does not reprint them. — Joe Kress (talk) 20:38, 15 March 2010 (UTC)

Scottish Calendar Switch
Although most people agree that Scotland changed New Year's Day in 1600 to Jan 1st, there is some dispute over whether or not it also changed to the Gregorian calender, before England did, on that date. This would make sense with Nova Scotia for example but since no one can come to definite agreement about the subject I think that at least the dispute should be given some mention in the article instead of just taking one line. I know this is obviously not the main point of the article but it is a factual moot point.


 * It seems clear that Scotland changed New Year's Day to January 1st from March 25th in 1600, by decree of James VI. (http://medievalscotland.org/history/calendar.shtml) It also seems clear that, for at least pragmatic reasons, Scotland's mercantile classes observed the Gregorian calendar after France and the Low Countries changed, as these were Scotland's major trading partners. (http://www.geo.ed.ac.uk/home/scotland/time.html) There is no remaining reference to this in the main article that I can see, despite the mention of "just taking one line," made in the above unsigned paragraph. Further, the "Timeline of Adoption" chart has a purple bar for "Nova Scotia 1630-1705" without any footnote or discussion of what this means (neither the purple colour, nor the specific mention of Nova Scotia). I am trying to research the Massacre of Glencoe, including MacIain's trip to swear allegiance on "New Year's Eve, 1691." It is not clear to me at all, whether this was the Old Style or New Style date, with some references even indicting that it was not clear to the participants at the time, as the offer was made by William III (of Orange, hence King of a New Style country) to the Chiefs of the Clans of Scotland, a country at least following, if not having officially adopted, the Gregorian Calendar at that time? It is also not clear to me, whether the dates of the Massacre refer to New Style or Old Style. I was looking for a little bit of help from this article on which calendar Scotland was following at the time and found none. Spartan26 (talk) 02:27, 28 June 2010 (UTC)


 * This topic comes up from time to time.  I believe the website you quote says that Scotland adopted the Gregorian calendar in 1600 but the consensus was that this website is unreliable (it made an elementary error in the explanation of leap years) and there was confusion between New Style (change of New Year's Day) and New Style (change from the Julian calendar).   Nova Scotia doesn't seem to be relevant - it was presumably a part of French Canada at the time and therefore using the same calendar as France.   It is commonplace for countries under Old Style to use New Style when corresponding with countries which use the Gregorian calendar but that does not affect their domestic arrangements.   I'm not an expert in Scottish history, but William and Mary followed James II in 1688, and I believe that a chieftain went to William in an attempt to forestall the massacre.   I don't know where William was at the time - I believe he was within the soon - to - be United Kingdom campaigning against the Scots.   So if the episode happened within Great Britain certainly it is dated according to the Julian calendar.   The only chance of it being dated by the Gregorian calendar is if the source is a continental (e.g. Dutch) one. 86.162.232.145 (talk) 09:12, 28 June 2010 (UTC)


 * Here is the discussion referred to by the above contributor., (third paragraph),, (with a link to the Leicester information site) and . 212.50.184.130 (talk) 10:14, 29 June 2010 (UTC)

My edit to Soviet calendar
A certain person, whom I am not allowed to name, being aggrieved at my suggestion that the Bolsheviks did not adopt the Gregorian calendar in 1918, initiated an SPI with the clerks and applied for protection on Gregorian calendar. The case was fully argued, although no evidence in rebuttal was submitted by the prosecutor. As the evidence has been removed from the record, I am repeating it here, suitably redacted.


 * Numerous sources, such as The Oxford Companion to the Year, say that Russia might not have adopted the Gregorian calendar.  Is it really credible that a virulently atheistic  dictator whose mind was affected by syphilis would have adopted a calendar bearing the name of a Roman Catholic pope?


 * To support his claim that Russia adopted the Gregorian calendar [redacted] would have to cite a reliable source stating that.  He hasn't, which suggests he can't.


 * These intensely violent revolutions all follow a similar pattern.  In Pol Pot's Cambodia in 1975 the Gregorian calendar introduced by the French was swept away and the date was set back to "Year Zero".   In revolutionary France at the end of the eighteenth century again the Gregorian calendar was swept away, the date was set back to Year 1 and a totally different calendar was introduced.   This had twelve months of thirty days, divided into three ten - day weeks plus five or six epagomenal days at the end, the sansculottides.   The new calendar was observation -  based, the year beginning on the day of the autumnal equinox, when the revolution started.   The names of the months describe aspects of the seasons.


 * The Bolsheviks drew a lot of inspiration from the French revolutionaries, and it is documented that the leaders gave serious consideration to introducing a French Revolutionary style calendar.  They went some way towards it - 360 days were divided into 72 weeks of five days each.   Six of these weeks make a thirty - day month and the sansculottides were accounted National Holidays, of which there were five (six in leap years).   There is nothing Gregorian about that.


 * [redacted] says the "New Calendar" was not devised till 1923.  Taken at face value, that means nobody ever introduced a new calendar  before 1923.   If that were true, up to 1923 we were all notching lines on pieces of bone marking off the dates in successive lunar months.   What is this New Calendar that was unheard of until 1923?   Calendar construction is a branch of mathematics that was as available in 1918 as it was in 1923.   To devise a suitable intercalary cycle you use continued fractions - the longer the fraction  the more accurate the ratio you come up with.   All the mathematical models were accessible in 1918.


 * Omar Khayyam suggested eight leap days in 33 years.  Isaac Newton proposed that the only centennial leap years should be those exactly divisible by 500, and years exactly divisible by 5000 should be "super leap years" in which February would have 30 days.   This gives a mean year (to four decimal places) exactly the same as the Meletian.   It is unduly complicated, since February is given three possible lengths, and there are three nested cycles, which produce unacceptable jitter.

A similar number of nested cycles feature in John Herschel's proposal, in which years exactly divisible by 4000 would not be leap years. Less jittery is Professor Maedler's proposal to omit one leap day every 128 years, but then the Easter tables don't work.

[redacted]'s argument does not hold water, but it is an abuse of process to run to the clerks every time somebody makes an edit which someone does not agree with.

[redacted] has accused me of "conflating", but he is conflating Gregorian and New Style. They are not the same thing. The Gregorian calendar includes rules for calculating the date of Easter. The Bolsheviks didn't adopt the Gregorian calendar and therefore those rules didn't come into force. They tried to stop the observation of Easter, but did recognise the Orthodox festival date. This we know because on Orthodox Easter eve they scheduled films on state television to encourage people to stay indoors rather than going to church. Miletian (talk) 14:41, 21 March 2010 (UTC)

Eastern European calendar: Naming proposal
On this glorious Easter Tuesday, united around the world, here is an update on the progress of the ballot.


 * Option 1 - Meletian calendar - 1 vote (recommended option)
 * Option 2 - New calendar (Eastern churches) - no votes (this option is not recommended)
 * Option 3 - No change - 2 votes (this option is not recommended)
 * Option 4 - "Revised" Julian calendar - no votes (this option is not recommended)

To vote by proxy, write QUICKVOTE and sign with four tildes. If you want your proxy to vote in a particular way, add the option number in brackets. Thus QUICKVOTE (1) means your vote will be cast in favour of Option 1.

The tilde is the wavy line ~ sometimes placed above n (in Spanish) or a or o in Portuguese where, following the medieval Latin copyists, it marks the omission of a following letter n.

This is not the place to vote. Click on this link Talk:Revised Julian calendar, read the manifestos and then add your vote underneath the others.

Uma Paschoa feliz a todos. O povo unido jamais sera vencido. 212.85.12.219 (talk) 17:48, 6 April 2010 (UTC)

Why drop 10 days?
I've never understood why they decided to drop 10 days. I understand that the motivation was the discrepancy between the official date of the equinox (March 21) and the actual date (around March 11), but it seems to me that they could've solved that discrepancy just as well by changing the *official* date to March 11 to match the actual date, rather than dropping 10 days, and from that point adopting the new leap year rule (thus meaning that the present difference would only be 3 days instead of 13). And that would've been a much more practical option, as it would not require drastically shortening a month, nor immediately creating a large discrepancy between the calendars of Gregorian-using and Julian-using nations (indeed, there would've been no discrepancy at all until February 28, 1700, which would be followed by March 1 Gregorian/February 29 Julian). Why did they choose to go the route they did? Was the March 21 date seen as somehow sacred due to it being chosen by the Council of Nicea? XinaNicole (talk) 21:50, 13 April 2010 (UTC)


 * There's a big cover - up going on here.  The vernal equinox wasn't falling on March 11 at all - it was falling on March 10.   Clavius (the new calendar's technical expert) knew this perfectly well, and by implication so did Pope Gregory XIII.


 * Something else they hushed up - the canons of the Council of Trent (i.e. binding rules which can only be changed by another General Council) directed that the dates of any reformed calendar must coincide with those of the Julian calendar at the time of the Council of Nicaea.  Clavius' calendar doesn't do that.


 * He also introduced an inaccurate leap year rule and, to add insult to injury, Gregory directed that this rule must be used "forever", although Pope Benedict is competent to change that.


 * The correct leap year rule, introduced by Eastern European governments at the prompting of the Orthodox Church, correctly aligns the new and old styles at the time of the Council of Nicaea.  It works on a 900 - year cycle - thus, from inception, the centennial leap years are 1600, 2000, 2500 (i.e. 1600 + 900), 2900 (i.e. 2000 + 900), 3400, 3800 etc.


 * The reason why a big chunk was taken out of the calendar has to do with the Catholic rules for observing saints' days which clash with movable feasts.  If Easter had moved out of its March 22 - April 25 slot those rules would have had to be recast.


 * To learn the truth about this, click on the "article" tab, then the "history" tab, and then click on "14:49, 6 April 2010". 212.85.12.187 (talk) 18:36, 19 April 2010 (UTC)


 * The "cover up" was about the 30 years of age of Jesus when he was crucified, much more like a "method of reasoning" than "an evil conspiracy". Rursus dixit. ( m bork3 !) 10:34, 23 April 2010 (UTC)


 * You're right XinaNicole! The reason was of course the Easter. The 10 days adjustment was in order to "reset" the calendar to the approximate state of the Julian calendar in the years around the crucifixion of Jesus Christ, abt 30-40 AD. The reasoning, I believe was based on the idea that the computation of the Easter Day should lead to a Sunday that exhibited the same Moon phase as it occurred at the crucifixion. There are technicalities involving the Golden Number, a virtual Moon, and I believe, the Jewish Pesach, but that is off-topic for the number 10. Rursus dixit. ( m bork3 !) 10:25, 23 April 2010 (UTC)


 * You are too charitable to the papacy.  The power - hungry ways of the bishop of Rome split the Roman church off from the rest of Christendom in AD1054.   Nicaea (AD325) was the first Oecumenical Council (i.e. it passed canons which the whole church agreed to observe).   Canon 6 divided Christendom into three provinces - Alexandria, Antioch and Rome - each governed by their own bishop.


 * Then the bishop of Rome claimed that he had the power to tell the other Patriarchs (including the newly created ones of Constantinople and Jerusalem) what to do!


 * He then interfered with the core statement of faith - the Nicene creed - adding the word filioque to the phrase "the Holy Spirit, which proceedeth from the Father", to make it read "which proceedeth from the Father and the Son".


 * The last pope promised to remove these words but we're still waiting.


 * The Council didn't agree a canon anathemising any interference with the calendar because they never envisaged that anybody would try such a thing.  What they did say, however, was that everyone should observe Easter on the same day (which they did until the Catholic church unilaterally changed the rules in 1582).


 * The virtual moon to which Rursus refers runs on a 300 - year correction cycle.  The virtual (Mean) sun runs on a 900 - year correction cycle, so the two mesh together nicely. 195.195.89.70 (talk) 08:32, 24 April 2010 (UTC)

Effect of different year starting points on insertion of leap day
In the article "Gregorian Calendar", section titled "Beginning of the Year", it is not clear what effect the change to the beginning of the year had on the insertion of the leap day. The rule that leap days were inserted in years divisible by four implies, for example, that in 1600 (a leap year in both calendars) in Britain using the March 25th year start, the inserted leap day was 29 Feb 1600, i.e. 29 Feb 1600/01, but that in countries that started a new year on January 1st, the inserted day was 29 Feb 1600, i.e. 29 Feb 1599/1600 ?? If this is correct (and I'm not sure it is), this changes the number of days by which the two calendars appear to differ, for that one year period between leap-day insertions?

Whatever the truth is, might this section be a place to clarify this small point? Timequest (talk) 19:25, 8 June 2010 (UTC)


 * All countries using the Julian calendar, regardless of how they numbered their years, added an extra day simultaneously (either 29 or 24 February). It was added in a year evenly divisible by four only if the year began on 1 January. Between 1600 and 1752, Scotland and England both used the Julian calendar, but Scotland began its numbered year on 1 January while England began its numbered year on 25 March. So the extra day in Scotland was 29 February 1600, while in England that same day was called 29 February 1599. I think all countries/provinces/cities that adopted the Gregorian calendar also began their Gregorian year on 1 January, so all of them followed the divide by four rule (except most centennial years). — Joe Kress (talk) 01:16, 9 June 2010 (UTC)

Edit request from Rebekah-16, 28 July 2010
editsemiprotected

Your Articale says 'In fact, any five consecutive months not containing February contain exactly 153 days.' However, if you start with a month that has 30 days, eg. April, the total is 152 which means that this is wrong, it should either be taken out or ammended to say 'In fact, any five consecutive months not containing February, that start with a month containing 31 days, contain exactly 153 days. However if you start with a month containing 30 days, the total is 152 days.'

Rebekah-16 (talk) 09:48, 28 July 2010 (UTC)

'In fact, any five consecutive months not containing February contain exactly 153 days. The statement is correct. If the first of the five months is April, June or September, which have 30 days, then the five months have two consecutive months of 31 days and the fifth month has 31 days bringing the total to 153 days. Karl (talk) 12:08, 28 July 2010 (UTC)


 * (edit conflict) Actually, it is 153 days because both July and August have 31 days and they consecutive. Listing the month lengths gives:


 * {| class="wikitable"

! Month ! Number of Days
 * January
 * 31
 * February
 * 28/29
 * March
 * 31
 * April
 * 30
 * May
 * 31
 * June
 * 30
 * July
 * 31
 * August
 * 31
 * September
 * 30
 * October
 * 31
 * November
 * 30
 * December
 * 31
 * }
 * September
 * 30
 * October
 * 31
 * November
 * 30
 * December
 * 31
 * }
 * December
 * 31
 * }


 * Adding these up in groups of five then gives:


 * {| class="wikitable"

! 5 Month Range ! Number of Days
 * January - May
 * 151/152
 * February - June
 * 150/151
 * March - July
 * 153
 * April - August
 * 153
 * May - September
 * 153
 * June - October
 * 153
 * July - November
 * 153
 * August - December
 * 153
 * September - January
 * 153
 * October - February
 * 151/152
 * November - March
 * 151/152
 * December - April
 * 151/152
 * }
 * September - January
 * 153
 * October - February
 * 151/152
 * November - March
 * 151/152
 * December - April
 * 151/152
 * }
 * December - April
 * 151/152
 * }

Therefore, the article is correct as it is. Hope this helps.  Set Sail For The Seven Seas   182° 42' 30" NET   12:10, 28 July 2010 (UTC)


 * This relationship is the basis of the 30.6 days (i.e. 153/5) constant that appears in many calendar algorithms, for example this one which is the basis of a computer programme which allows anyone to print their own diary pages for any period. 92.24.42.70 (talk) 10:05, 29 July 2010 (UTC)

Links to Formal Authorities
I think that it would be of interest to have a Table giving, for each country or jurisdiction, links to the actual original legislation (or similar) that required the use of the Gregorian Calendar, and to associated material giving details. Since readers have a search facility within pages, it would be best in chronological order. Another column should show how close to the original the linked material is.

The first entry would link to the Papal Bull, the Six Canons, and the Opera Mathematica V.

The "Great Britain and Colonies" entry would be to the Act of 1751, as nearly as possible (e.g. Statutes at Large 1765).

There should be a final entry for ISO 8601.

I don't know of any links for other places; but those who do can add them.

82.163.24.100 (talk) 20:33, 12 October 2010 (UTC)

Current period explanation
Oriel36 made a recent series of edits which tries to explain the operation of leap days in several years near the present. I feel that if it is retained, this passage needs clarification and style improvements. Before attempting this, I would like to know if others feel the passage is necessary at all, or should it just be removed? Jc3s5h (talk) 14:42, 22 October 2010 (UTC)

The weekday intervals in section "Leap Seconds and Other Aspects":
This is regarding the paragraph that states:

"A smaller cycle is 28 years (1,461 weeks), provided that there is no dropped leap year in between. Days of the week in years may also repeat after 6, 11, 12, 28 or 40 years. Intervals of 6 and 11 are only possible with common years, while intervals of 28 and 40 are only possible with leap years. An interval of 12 years only occurs with common years when there is a dropped leap year in between."

This paragraph is almost completely correct; however, it misses the 5-year intervals. The repeating pattern as long as there is no leap-year dropped is 6-5-6-11 (6+5+6+11=28). The days of the week before leap day are on one rotation and the days of the week after leap day are on a different rotation. For example Jan 1st fell on a Sunday in 1978, 1984, 1989, 1995, and 2006. March 1st fell on a Wednesday in 1978, 1989, 1995, 2000, and 2006. Thus, the rotation of intervals between years with the same weekdays would be 6-5-6-11 for weekdays that occur before leap-day and 11-6-5-6 for weekdays that occur after leap day.

I am adding "5" to the information and avoiding changing any wording. I'll let others add the 6-5-6-11 pattern information, if someone desires to add it.

208.88.11.176 (talk) 16:36, 29 October 2010 (UTC)

Random Observer


 * I question the need to include this level of detail at all. Sure, the 28 year cycle is mildly interesting. The only people I can think of who would be interested in the rest are people who's resources are so limited they have to reuse calendars because they can't afford to buy new ones (certainly there are billions of people who can't afford calendars, but will they have access to Wikipedia?) and people who like to perform feats of mental calculation. Jc3s5h (talk) 17:32, 29 October 2010 (UTC)

Names for days of the week
When was the names of the week origenate ie Sunday, Monday, Tuesday etc. —Preceding unsigned comment added by 99.105.36.208 (talk) 18:12, 15 December 2010 (UTC)


 * See Week-day names. We suspect that the planetary week (Sunday–Saturday) began within Ptolemaic Egypt about 200 BC, but the earliest mention of the planetary week occurs in a Pompeian graffito which includes the weekday "dies Solis" (Sunday) within a 60 AD date. The earliest surviving explanation comes from Vettius Valens about 160 AD. The order Sunday–Saturday matches the Hebrew week which had numbered days, first day–sixth day plus the Sabbath, ever since the Babylonian exile during the sixth century BC. — Joe Kress (talk) 05:54, 16 December 2010 (UTC)

Minor edit request.
The article currently contains this sentence: "In addition to the change in the mean length of the calendar year from 365.25 days to 365.2425 days, the Gregorian calendar also dealt with the past accumulated difference between these lengths (10.8 minutes)."

It then explains that the discrepancy leads to about a ten day shift. Based on that, I am guessing the 10.8 minutes in the parentheses should be 10.8 days.

Lumbind (talk) 18:39, 5 December 2010 (UTC)


 * Its the accumulated error. Its 10.8 minutes per year, but over the years it built up to about 10 days. --John (User:Jwy/talk) 18:46, 5 December 2010 (UTC)
 * Trying to work the math: 10.8 minutes/year x 1582 years = 17,085.6 minutes = 284.76 hours = 11.865 days.  --John (User:Jwy/talk) 20:00, 5 December 2010 (UTC)


 * I have made a minor edit to move the 10.8 minute figure closer to the quantities it is related to. Jc3s5h (talk) 20:06, 5 December 2010 (UTC)

Remember, 10.8 minutes/yr is the difference between Gregorian and Julian calendars, not the actual error that was screwing up the date of Easter. The Gregorian-Julian diff is meant to partly compensate for the actual 11.25 minute/yr difference between the tropical year and the Julian Calendar. That's the figure you need to use, and the time span that inacuracy ran for, was about from 325 AD to 1582 AD = 1257 years. Multiplied by 11.25 min error per year gives 9.82 days. Close enough to 10 days. S B Harris 07:01, 31 December 2010 (UTC)

File: „Permanent_calendar.png“
Fehler, sorry. siehe diskussion "Joe Kress" ,see please Joe Kress|talk --LenderCarl (talk) 20:03, 28 January 2011 (UTC)

Edit Request
There's a typo. It's "prEcession of the equinoxes", not "prOcession of the equinoxes".

I can't find an edit button or I'd fix it myself.

JustDiploid (talk) 22:29, 3 February 2011 (UTC)

Gregorian Calendar is not the Christian Calendar
It is correct to state that the Gregorian Calendar is colloquially regarded as the Christian Calendar. It is also correct to state that the sole authority of this Calendar lays with the Holy See of the Vatican. One may conclude from such that it makes this calendar Christian. But this Calendar has no basis in canonized Christian literature. The early christian Calendar was Jewish. It was probably not entirely similar to the current Hebrew calendar, as there are reasons to believe that the Jewish-Christian community did not alltogether agree with the intercalation practice based on the Metonic cycle. The Gregorian Calendar is incorrectly referred to as a Calendar in its own right. In matter of fact, the Gregorian Calendar is merely a revision of the original Julian Calendar of the Roman Empire. It is obvious that the Catholic Church is heir to the Calendar of the Empire, but not its maker. The names of the days, and months clearly points out that what is here colloquially called the Gregorian Calendar is a heathen calendar, a revision of the Calendar introduced by Julius Ceasar at the entrance of the new age of the Roman Empire. The Roman Catholic Church will by all probability not introduce a Christian Calendar unless Parousia is the emergency. --Xact (talk) 21:09, 6 February 2011 (UTC)


 * Several of your points are already included in the article. For purposes of the lead of the article, we are interested in giving popular names for the topic of the article so people will know whether they have probably arrived at the page they are looking for. If the name is illogical, that can be explained later in the article. Jc3s5h (talk) 22:46, 6 February 2011 (UTC)

century rule diary software check tip
I don't know if anyone else did this, but back in the 1990s, I was part of a Management Consultancy Team in the Department of Education, NSW. Part of our job was looking at new software and hardware, as the computer revolution was only just hitting the Public Service in a big way here. I was aware that the year 2000 was NOT a leap year, and quite surprised that many people just assumed it would be, because 1996 was one.

Every time I checked some software that included a calendar, I would ask it to look up 29 February, 2000. Quite often it would be there! And it shouldn't have been, should it? This made me think the people who had composed the software were slovenly. And of course, 2000 was not a long way away from 1996, so that error could have REAL effects on payrolls and all sorts of administrative things.

Well, I recommend that anybody evaluating such software now have a look at 2000 anyway, even though it is in the past, and a look at 1900, 2100, which, of course, should not be leap years. Myles325a (talk) 08:33, 15 February 2011 (UTC)


 * Actually, 2000 WAS a leap year! As explained in the article, years divisble by 400 (such as 1600, 2000, 2400, etc.) are leap years.AstroLynx (talk) 09:50, 15 February 2011 (UTC)


 * Yes, in every 3 out of 4 centuries, we have a leap year at the end of a century when we should be "skipping one." That fact kept the year 2000 from being used to emphasize the Gregorian calender. 1900 was not a leap year and 2100 won't be, either. S  B Harris 18:44, 15 February 2011 (UTC)

OP myles325a back here. I lay in bed, and then suddenly woke up, sat bolt upright and screamed as I remembered what I had written. It was late, I was tired, and I had got it round backwards. Yes, 2000 was only the second century year (after 1600) to be a leap year, in the Gregorian Calendar. What I used to do when checking diary software was check to see if the date 29 Feb 1900 was there (it should not be as 1900 was NOT a leap year), and if Feb 28, 1900 was correctly placed as the last day of that month, I would then look up 29 Feb 2000, to see if the geekboys computer programmers had got BOTH the century AND the quatrocentury leap year rules right. Myles325a (talk) 04:11, 16 February 2011 (UTC) this is not happan in future —Preceding unsigned comment added by 124.43.8.162 (talk) 08:55, 22 March 2011 (UTC)

Calendar seasonal error
This section of the article is entirely wrong. The summer solstice has no relevance to the Gregorian calendar, as the stated purpose of the reform was to restore the spring equinox to March 21st. The chart should show when the northern hemisphere spring equinox falls in the calendar. Doing that properly is no small matter, however, because the reference meridian for the Gregorian reform was left undefined. Should the equinox be calculated for Alexandria or Jerusalem mean solar time or Universal Time or something else? Also, should dates be considered to start at sunset, which was the original Christian practice, or should they be calculated according to civil midnight, which is the modern practice? The chart could show several thousand years into the future but if so then the equinox moments should be based on numerical integration and the NASA Espenak-Meeus polynomials for Delta T correction. The mean tropical year also has no relevance to the Gregorian calendar -- the relevant astronomical target is the mean spring equinox year of the northern hemisphere, that is the mean northward equinoctial year, which is presently 365 days 5 hours 49 minutes 0 seconds. Kalendis (talk) 02:21, 17 May 2011 (UTC)


 * It is doubtful that the Roman Catholic Church is still in charge of the Gregorian calendar. If that church tried to change it, it is quite possible the change would be rejected or ignored by all the countries and international organizations that have adopted it. These countries and international organizations might be more interested in how well the calendar tracks the mean tropical year, notwithstanding the original purpose of the calendar. Jc3s5h (talk) 03:45, 17 May 2011 (UTC)

Edit Request - Correction of orbit time of Earth - Cancelled
There appears to be an inconsistency between the stated annual Earth orbit of 364.2425 days and the known time of 365.253663004 days - See Earth in WikiPedia. Thinking about it, it seems logical that 3 days be subtracted from the 400 year cycle if the Earth were indeed going faster than the Julian Calendar. Would someone, perhaps the article author, take a look at this please. I would attempt this myself, but I'm not 100% certain that this is not simply a misunderstanding of terminology, and it also seems quite complex to make this change because, if I'm right, it involves nearly everything in the article. Thank you. Alex146 (talk) 21:15, 5 March 2011 (UTC)
 * I think you may be confusing the sidereal year (365.2563 days) with the tropical year (365.2422 days). The difference between the two occurs because the Earth's axis is moving. The Gregorian calendar year (365.2425 days) is an approximation to the tropical year.--Oz1cz (talk) 23:10, 5 March 2011 (UTC)


 * You meant 365.2425 days, right? That is the average length, in days, of a calendar year when using the Gregorian calendar. The average is taken over the 400 year cycle of leap days. It does, of course, differ a bit from the current average year length, in part to allow a simpler pattern of leap days, in part because the correct value was not known as well in the 16th century as it is now, and in part because the value is constantly changing. Jc3s5h (talk) 23:14, 5 March 2011 (UTC)


 * Yes, 365.2422 was a typo, and I think Jc3sh5 meant 365.2425. I understand both explanations, but, sorry, I'm still confused, at least intellectually.  I agree that a year exactly equal to 365.25 would mean that every four years would be a leap year.  In order to require three less leap years in 400 years, it would seem that the actual time would have to be greater than 365.25.  Yes, I have always heard the 364.2425 time, but now that I think about it, it still does not make sense.  Can I trouble you, please, for a better explanation?  Thank you.  Alex146 (talk) 01:04, 6 March 2011 (UTC)
 * If you can see that ADDING a leap day INCREASES it from 365 to 365.25, can you not see that FAILING to add that day occassionally, must move it the other way again, and make it slightly LESS than 325.25? As for the amount, instead of being .25 days per year added, it's .25 days - (3 leapdays in 400 years missed) = .25-.0075 days/year = .2425 days/year. S  B Harris 01:29, 6 March 2011 (UTC)


 * The way I like to calculate it is to observe that the greatest time span in the rule is 400 years. In that span there are 100 years divisible by 4. All but 3 of these (the years that are divisible by 100 but not by 400) are leap years, so there are 97 leap years. The number of days then is 97⋅366 + 303⋅365 = 146,097. Divide that by 400 and you get 365.2425. Jc3s5h (talk) 14:12, 6 March 2011 (UTC)


 * I just grokked it. (Hope everyone knows that term - :-)>)  I missed the comment about the axis changing, thinking it was the "normal" difference between sidereal and tropical (or one of the other terms).  The comment about adding one day if its 365.25, and then subtracting a little bit if you subtract 3 days in 400 years, jostled my brain, and then I remembered about, and then researched, axis precession over 26,000 years.  Thank you everyone for responding so quickly.  I appreciate it. Alex146 (talk) 01:39, 7 March 2011 (UTC)
 * Yes, due to the precession of the equinoxes, the tropical year is a little SHORTER than 365.25 days, while the siderial year is a little LONGER than 365.25 days. The difference is about 20 minutes. So Spring arrives 20 minutes before the Earth has made it all the way around the Sun and it's Spring that we care about (the vernal equinox and change in seasons) not the siderial year or Earth orbit (which only changes the astrological signs). That 20 minutes is about 1/26,000th of a year, and there you are. So the astrological signs change by 20 minutes a year, and that has screwed things up for astrology in the last 2000 years, but for the calender, it's the seasons that count, not astrology. We just keep "pretending" with astrology (as you may know, the astrological signs aren't where the Sun is, there days, due to this very problem of the calender synching with the tropical, not the siderial, year). S  B Harris 02:30, 7 March 2011 (UTC)

The mean tropical year is currently 365.24219 days. Many countries use what they call the "new calendar" in which the date is currently the same as the Gregorian, but they have not approved the Gregorian leap year rule. This has significance because some churches have approved a different leap year rule, in which 218 years in 900 years are leap years, rather than 97 in 400 as under the Gregorian rule. This gives the more accurate length of 365.24222 days (correct to one day in 44,000 years rather than the Gregorian's one day in 3,323 years). It has been suggested that the Gregorian calendar also goes onto a 900 - year cycle, in which case the sequence of centennial leap years will be 1600, 2000, 2500, 2900, 3400, 3800 etc. 86.148.169.6 (talk) 20:09, 7 March 2011 (UTC)


 * What "many countries" are using this "new calendar"? In what sense is 365.24222 "correct to one day in 44,000 years" at representing the mean time between vernal equinoxes, 365.242374 days currently?  The Gregorian calendar fits that number to within one day in 7936 years, while this "new calendar" fits it to within one day in 6588.  Of course, the earth's rotation is slowing, and the length of a Vernal year in days is likely to go down further as a result, but we also haven't had to add any leap seconds lately, so who knows? The Monster (talk) 14:21, 16 September 2011 (UTC)


 * The "New calendar" is another name for the Revised Julian calendar whose article lists the many Eastern Orthodox Churches that have been adopted it, though it has not been adopted by the largest, the Russian Orthodox Church. Its centennial leap years are 1500, 2000, 2400, 2900, 3300, 3800, etc., where 1500 is proleptic, so they follow a 900-year cycle averaging 365.242222 days per year. The associated countries adopted the Gregorian calendar as their civil calendar before 1923; then many of their national churches adopted the Revised Julian calendar in subsequent years. Anonymous argues that the Revised Julian calendar replaced the Gregorian calendar even for civil purposes in these countries. The "Exigian" calendar with centennial leap years of 1600, 2000, 2500, 2900, 3400, 3800, etc. is his personal proposal. I am guessing that "Exigian" honors Dionysius Exiguus even though he did not propose any modification of the leap year rules of the old Julian calendar, which has a leap year every four years, including all centennial years.


 * Both 44,000 years and 3,323 years are errors relative to a rounded version, a little more than 365.242199 days, of Simon Newcomb's mean tropical year at J1900.0. However, the mean tropical year changes over thousands of years. Newcomb himself stated that it was 365.24219879 − 6.14T, where T is the number of centuries since 1900. This formula predicts that it would be 365.24219265 days at 2000. A modern value for the mean tropical year is 365.2421896698 − 6.15359T since 2000. The latest formula changes the length of the mean tropical year for 2000 from the value predicted by Newcomb. Unfortunately, neither of these formulas can be extended beyond about 4,000 years, certainly not 44,000 years. Anonymous refuses to accept the vernal equinox year. Furthermore, both formulas use the uniform time of Ephemeris or Terrestrial Time where each second is the same length as any other. But Earth is currently slowing down.


 * Steve Beyers has an excellent comprehensive discussion of the various astronomical years over thousands and millions of years, first without Earth's slowing rotation and then with it. Irv Bromberg also discusses this, less comprehensively. — Joe Kress (talk) 07:05, 19 September 2011 (UTC)

Calibration
Please indicate what point in time that the Gregorian calendar calibrates with.130.56.92.62 (talk) 15:03, 19 May 2011 (UTC)
 * bump130.56.92.62 (talk) 15:11, 19 May 2011 (UTC)


 * It is in fact not properly defined. Those who mattered in 1582 knew the Julian Date and its rules, and the Papal Bull just defined the differences. ISO 8601 has "The Gregorian calendar has a reference point that assigns 20 May 1875 to the calendar day that the “Convention du Mètre” was signed in Paris.", but that is not a reproducible definition.


 * I propose that the Solar Eclipse of 1999-08-11 Wed be used. It was visible (partial; weather permitting, which I think it did) at Greenwich, and in many more countries than most other eclipses (Cork to Calcutta, roughly).  No other eclipse within thousands of years, at least, will have had a reasonably similar path and time-of-day, and a civilisation can calculate eclipses for at least thousands of years - see Fred Espenak's tables at NASA.  It cannot be re-produced; but it can be determined in retrospect.


 * 94.30.84.71 (talk) 18:46, 26 May 2011 (UTC)

Description
Article has "A Gregorian year is divided into twelve months of irregular length, with no regular relationship among their lengths:".

That is untrue, or at least exaggerated. Starting from the end of February, the accumulated days at each month-start up to the start of next February are the nearest integers to a suitable straight line fit (slope of 30.6) - and February just passes the residual time until the year-length rules show that March is due. That's the basis for Zeller's Congruence. It seems clear enough that those who decided the month-lengths had essentially that concept of smoothness in mind, whether or not they knew it. 94.30.84.71 (talk) 18:57, 26 May 2011 (UTC)

Sockpuppets
I just twigged on this ... I was a fool not to have spotted it before. D(e)r Lero is an incomplete anagram of the German word kalender. The first "e" is in parentheses because the English word is calendar. LenderCarl is a better anagram of both words, and LenderKarl manages to get all the letters in. Apart from this, all three of them are single - purpose accounts (the same purpose) and they all live in Saxony. LenderKarl was created on 16th February, 2009 and has been a sleeper since then. 92.234.23.201 (talk) 17:07, 5 July 2011 (UTC)

Future calenders
Is it possible that we will use a different calender in the near future? Have there been proposals to implement a more accurate calender in any western countries? Pass a Method  talk  13:31, 21 October 2011 (UTC)


 * I have not heard of any new (that is, the last 20 years or so) proposals for western calendars that are gaining any traction. I think a major reason for this is that beginning in the 1930s it became more and more clear that the rate of rotation of the earth is slowing down; see ΔT and Leap second. Celestial mechanics is used to find the relative position of the Sun, March equinox, and Earth, and thus calculate the length of the tropical year. Since celestial mechanics obeys the theories laid down by Newton and Einstein, the unit of time must be constant. Our best way to measure time in constant units is the atomic clock. So it is atomic clock seconds that is used in celestial mechanics. But the Earth is slowing down, relative to atomic clock seconds, in an unpredictable way. So although we might be able to compare the accuracy of various calendar proposals if we were counting days of 86,400 atomic seconds, that's not what we count with calendars. For calendar purposes, a day is an observation at a particular point on the earth that the sun comes up and goes down. Those kind of days are too unpredictable to decide which calendar proposal is most accurate. Jc3s5h (talk) 14:00, 21 October 2011 (UTC)


 * So is the Gregorian calender more accurate than the hebrew, islamic, chinese, baha'i, hindu and persian calenders? Pass a Method   talk  21:25, 27 October 2011 (UTC)


 * I don't know. One would have to figure out what is important to users of those calendars, and figure out by how much they miss the user requirements at various points in the future. If the amount they miss by is similar to the uncertainty in ΔT, then we can't tell if they are better or worse than Gregorian. Gregorian is about as good as the uncertainty in ΔT. If one or more of those calendars misses the user requirements by substantially more than the uncertainty in ΔT, then it is "worse" than Gregorian.


 * I don't really think of any of those as "western", but by the time calendar accuracy becomes a problem, the meaning of "western" will probably have changed or disappeared. Jc3s5h (talk) 21:51, 27 October 2011 (UTC)


 * So which is more reliable? A lunar or solar calendar? Pass a Method   talk  23:32, 27 October 2011 (UTC)


 * One way to look at that question is to examine how accurately the position of the moon can be predicted, and compare it to how accurately the rotation of the earth can be predicted. I don't know the answer to that. Another way to look at it is, what is important to a user about the position of the moon, and how well does the calendar satisfy the need. By the way, the Gregorian calender incorporated a lunar calendar too, which is used in computing the date of Easter. See Computus. Jc3s5h (talk) 23:38, 27 October 2011 (UTC)


 * The best option to my knolwedge is the NUCAL: http://nucal.blogspot.com New Universal Calendar (Nuevo Calendario Universal in Spanish) — Preceding unsigned comment added by 62.83.35.154 (talk) 21:08, 14 December 2011 (UTC)

Difference between Gregorian and Julian calendar dates
The Table is over-simplified.

From the Gregorian point of view, the difference changes in mid-March, when the Julians "wrongly" have a February 29th that the Gregorians omit. But, from the Julian point of view, the difference changes in mid-February, when the Gregorians "wrongly" omit a February 29th that the Julians have.

The tabulation should reflect that. 94.30.84.71 (talk) 12:51, 12 December 2011 (UTC)


 * See please http://commons.wikimedia.org/wiki/Wikitable_calendar or http://commons.wikimedia.org/wiki/File:Permanent_Calendar_gregorian.png page on the top right.--LenderKarl (talk) 15:09, 9 January 2012 (UTC) or LenderCarl for English pages or articles

Incorrect Typing Japanese Era Name
There is a typing mismatch about the Japanese era name. It is referred as Gengo when actually it is called Nengo. Please refer to http://en.wikipedia.org/wiki/Japanese_era_name for more details.

msspereira (talk) 10:52, 22 December 2011 (UTC) User msspereira on 22nd December 2011


 * Corrected. — Joe Kress (talk) 07:15, 23 December 2011 (UTC)

Orthodox churches
The british orthodox church, like finland, uses the gregorian calendar.. "The Protocol also permits the British Orthodox Church to follow the Gregorian Calendar" http://britishorthodox.org/aboutus/ 94.11.63.20 (talk) 23:35, 22 December 2011 (UTC)


 * About the British Orthodox Church states "The Protocol also permits the British Orthodox Church to follow the Gregorian Calendar for solar festivals ..." This says nothing about lunar festivals, that is, Easter and all Sundays related to it. Almost all Orthodox Churches, whether or not they have adopted the Revised Julian calendar or New calendar for solar festivals like Christmas, celebrate Easter and related Sundays according to the Julian calendar. The Finnish Orthodox Church, almost unique among Orthodox Churches, celebrates Easter and related Sundays according to the dating rules of the Gregorian Easter and dated in the Gregorian calendar. The British Orthodox Church page states that 19 June 1994 was Pentecost Sunday. That is the Gregorian date corresponding to the Julian date of 6 June 1994, which is seven weeks after the Julian Easter Sunday date of 18 April 1994 (1 May 1994 Gregorian calendar). The Finnish Orthodox Church would have celebrated Pentecost on 21 May 1994 Gregorian, seven weeks after the Gregorian Easter date of 3 April 1994. So the British Orthodox Church is not like the Finnish Orthodox Church in this respect. The normal practice of giving the dates of all Orthodox celebrations in the Gregorian calendar, even those originally in the Julian calendar and calculated according to the Julian computus, is an unavoidable complication. — Joe Kress (talk) 07:07, 23 December 2011 (UTC)

Accuracy
It is necessary to clarify or to change the following sentence from section "Accuracy":

However, because of the precession of the equinoxes, the error with respect to the vernal equinox (which occurs, on average, 365.24237 days apart near 2000[56]) is 1 day every 7,700 years.

It is difficult to understand how the number 7,700 was obtained. Moreover, information in brackets is confusing since it implies quite another result instead of 7,700 (probably, the point is that the number 365.24237 is proper near 2000 and it changes, but it should be explained more clear). Besides in other language in Wikipedia I saw another number of years for this item (but also unclear). --D.M. from Ukraine (talk) 20:58, 13 April 2012 (UTC)


 * The difference between the average calendar year is 365.2425 days. The average vernal equinox tropical year, around the year 2000, is 365.24237 days. The difference between these two lengths is 0.00013. Dividing this number by 365.2425 we get 3.6×10-7, or one part in 2.8 million. We could think of this as 1 day in 2.8 million days, or 1 day in 7700 days. Jc3s5h (talk) 21:20, 13 April 2012 (UTC)


 * Really, these calculations are correct. I mistook earlier. But the item is more complicated, and probably several other causes of changes should be described. I doubt for 7,700 years to be close to correct answer. --D.M. from Ukraine (talk) 14:57, 14 April 2012 (UTC)
 * OK, now I see that the section is more or less good since there are some additional estimations below. But I suppose that there should be even more additional (maybe alternative) estimations. --D.M. from Ukraine (talk) 15:16, 14 April 2012 (UTC)

Changeover in North America
I feel that it would be helpful to provide more information about this. is a 'Map of the New-France about 1750'. I assume that the territories held by France and Spain would have been using the Gregorian calendar since the time when they were settled, while those held by Great Britain would have been using the Julian. So for example a person travelling from British Savannah, Georgia to Spanish St. Augustine, Florida in 1750 would have had to change their calendar. Likewise someone travelling from French Saint John, Acadia to British Port Royal, Nova Scotia.

Alekksandr (talk) 22:37, 27 April 2012 (UTC)

Inaccurate statement regarding mathematical formula
Hi, Haven't done this before. Hope I'm doing it right. My purpose is to get this corrected. If this is the wrong place, please let me know. Thanks.

Correct the paragraph?

This is a paragraph from the article: "Although the month length pattern seems irregular, it can be represented by the arithmetic expression L = 30 + { [ M + floor(M/8) ] MOD 2 }, where L is the month length in days and M is the month number 1 to 12. The expression is valid for all 12 months, but for M = 2 (February) adjust by subtracting 2 and then if it is a leap year add 1."

The statement portion I believe to be in error is : "The expression is valid for all 12 months, ..."

It should read as follows: "The expression is valid for 11 months, ..."

The statement is NOT valid for February.

So the entire paragraph should read something like:

"Although the month length pattern seems irregular, it can be represented by the arithmetic expression L = 30 + { [ M + floor(M/8) ] MOD 2 }, where L is the month length in days and M is the month number 1 to 12. The expression is valid for eleven months. For M = 2 (February) adjust by subtracting 2 and then, if it is a leap year, add 1."

Or maybe omit the entire paragraph? Was this expression used to originally establish the lengths back in the 16th century? If so, it needs to be here. If it was someone's later attempt to make more sense of the pattern, it's my opinion that it should be dumped. This is especially so since it fails to persuade the knowledgable reader that the months are somehow "not irregular".

Thanks for listening. Bdbluesman (talk) 21:02, 15 January 2012 (UTC)


 * I don't have any objection to either of your suggestions. The formula seems out of place in that section. The lengths of the months were determined by Julius Caesar in 46 BC (effective 45 BC) and have never been changed. The standard literary source, De die natali by Macrobius (c. AD 430), does not give any reason why these lengths were chosen. It only lists the months that received one or two extra days and where these days were placed within each month. The Gregorian change of dropping three leap days every 400 years did not even change the length of February.


 * Starting with March, the daycounts to the ends of the first eleven months are a good fit to a straight line of slope 30.6 and offset I think about 0.2; February is just what is left to complete 365 or 366 days. There should be a reference to Zeller's Congruence. 94.30.84.71 (talk) 13:00, 9 May 2012 (UTC)

20000 year cycle?
My Britannica CD makes brief reference to subtraction of the 400-year leap day for years divisible by 20000 (making average year of 365.24245 days). If anybody knows anything about the status of this notion or policy, it should be edited in.144.26.117.20 (talk) 16:04, 30 March 2012 (UTC)


 * Various enhancements to the Gregorian calendar leap year cycle have been suggested, but never adopted. Generally those suggestions were made before the invention of atomic clocks; we now know that the rotation of the Earth on its axis is a little unsteady, slowing down gradually, and somewhat unpredictable. This makes it impossible to predict exactly how many leap days will be needed in the next 20,000 years to keep the March equinox on March 21 (averaged over a reasonable number of years, say a century). So calendar reform beyond what we already have is pointless. Jc3s5h (talk) 18:14, 30 March 2012 (UTC)


 * The article is about the Gregorian Calendar, which by the authority of the Papal Bull Inter Gravissimas is perpetual. ISO 8601 is specifically about the Gregorian Calendar, only supposing its actual use.  If the calendar is changed, it will not be Gregorian - and persons named like Gregory or Julius should never allowed to be responsible for any changes. 94.30.84.71 (talk) 12:43, 9 May 2012 (UTC)

revision of table of differences between Gregorian and Julian calendars
In line with a change I requested (which has now been made) to the Julian Calendar article (Wikipedia), I have revised the subject table in THIS Wikipedia article. Notice when the difference between Gregorian and Julian grows by 1 day: when the GREGORIAN calendar goes from end of February to March 1 (in "00" year which is not a multiple of 400). I just pointed out in the Julian-Calendar article's Talk page that this is what will happen in 2100:

15 Feb. 2100 (Julian), which is 28 Feb. (Gregorian); 13 day difference.

The next day will then be:

16 Feb. 2100 (Julian), which is 1 March (Gregorian); 14 day difference.

2100 is not a Gregorian leap year, and that's why the Gregorian calendar jumps from 28 Feb. to 1 March. But at that point, the Julian calendar will still have Feb. 29 ahead in the year 2100. Do you see what I am saying? — Preceding unsigned comment added by 128.63.16.82 (talk) 21:20, 27 April 2012 (UTC)


 * It seems simplest to say that, from the Gregorian point of view, the difference increases by one day whenever the Gregorian Reform omits a February 29th which the Julian Calendar has included. From the Julian point of view, the difference increases by one day whenever the Julian Calendar includes a February 29th which the Gregorian Reform will omit. In the short interval between those two corresponding events, the difference is uncertain. 94.30.84.71 (talk) 13:01, 9 May 2012 (UTC)

The Calendar FAQ
Anyone intending to edit either the Article or this Talk should first become familiar with The Calendar FAQ - Frequently Asked Questions about Calendars. 94.30.84.71 (talk) 13:07, 9 May 2012 (UTC)

Alaska
The article now claims there was a discontinuity in the week when Alaska adopted the Gregorian calendar. I have not been able to find documentation on the legal mechanism through which Alaska adopted the Gregorian calendar (details below). I suspect, but cannot confirm, that any "discontinuity" in the week was due to Alaska being moved across what we now call the International Date Line, although then or now that imaginary line has no precise legal definition. I suspect it was not due to the change in calendar alone.


 * Crossing the Date Line inevitably causes gain or loss of a date, give or take one or more hours (with, in principle, maybe a part of an hour). Samoa (not American Samoa) did so in December 2011. Consider http://classiclit.about.com/library/bl-etexts/eapoe/bl-eapoe-three.htm. 94.30.84.71 (talk) 15:03, 9 May 2012 (UTC)

Details: In the United States control over standards of weights and measures is given by the constitution to the Congress. The states have been content to allow the federal government to regulate time of day and time zones. It is unclear whether the federal government has the authority to adopt a calendar, or whether that power lies with the states. In any case, all the states use, and some, like New York, have explicitly adopted, the Gregorian calendar. The Congress has never passed a statute requiring general use of the Gregorian calendar, but all the federal organs of government use it for their own purposes.

Alaska did not become a state immediately; for many years it was a territory of the US. Ordinarily when territory passes from the jurisdiction of a foreign government to US federal jurisdiction, many of the existing laws continue in effect. I have been unable to locate any legal action that caused Alaska to change from the Julian to the Gregorian calendar. Jc3s5h (talk) 14:10, 9 May 2012 (UTC)


 * That seems unimportant. This page should at most be interested in when and how dating in Alaska changed; the formalities are not relevant. But the legal situation seems clear enough : the (British) Calendar Act of 1751 made Great Britain and colonies in various parts of the world Gregorian, implementing a religious decision of 1582; the USA inherited British law; the Second(?) Amendment seems to prohibit altering that particular law; and $4M made Alaska American, so that the "British" law applied.  No US legislation was needed. 94.30.84.71 (talk) 15:03, 9 May 2012 (UTC)


 * I agree this article is not the place for these details. But I think the statement "the USA inherited British law" is over-broad; it certainly isn't true for Louisiana or Puerto Rico. Jc3s5h (talk) 15:12, 9 May 2012 (UTC)


 * The USA inherited British law at its formation. Louisiana formed no part of that; it was purchased later.  The purchase did not alter its calendar; but it altered the legal foundation thereof.  AIUI, Puerto Rico declined the opportunity of becoming a United State; Federal law applies, but the Puerto Ricans cannot vote for those who make it. It is in effect a colony of an ex-colony, and the Calendar Act must apply there. 94.30.84.71 (talk) 17:55, 9 May 2012 (UTC)


 * See International Date Line. — Joe Kress (talk) 06:34, 10 May 2012 (UTC)

Adoption in Europe
This may be near enough the right section for dealing with the British Colonies in North America; but Alaska is surely out of place in it. 94.30.84.71 (talk) 21:38, 9 May 2012 (UTC)

It seems wrong to express the change from Julian to Gregorian in days. No days were omitted; the sun continued to rise and set in the usual manner. It was dates that were omitted. 94.30.84.71 (talk) 21:38, 9 May 2012 (UTC)

Edits by Ewawer
Two edits by Ewawer have changed the order somewhat. Also, this passage was inserted: "The lunar part used the model proposed by Aloysius Lilius which involved a 10-day correction to revert the drift since Nicaea." There was indeed a lunar part, but the 10-day correction was associated with the solar reform, not the lunar reform. The lunar reform is explained in the "Lunar calendar" section.

I'm guessing the purpose of the edits were to make mention of the lunar reform in the history section, but I don't believe this attempt to explain the lunar reform is correct. Jc3s5h (talk) 12:44, 28 September 2012 (UTC)

October edits by Ewawer
The edits made on or near October 4 by Ewawer introduce errors and ambiguities. Specifically:


 * "The motivation for the Gregorian reform to the Julian calendar was to reverse the calendar drift since the First Council of Nicaea in 325 AD..." (emphasis added) can be read to understood that the drift between the calendar and some unnamed kind of year or astronomical event is the same magnitude after the Gregorian reform as before, but the direction of the drift is opposite.


 * "...the First Council of Nicaea in 325 AD set the relationship between the Julian calendar and the dating of Easter." Not exactly. They council set some goals, but the exact computation was not settled upon until Dionysius Exiguus some 200 years later, and that computation took considerable additional time to spread throughout all Christendom. See Computus.


 * "The length of the Julian calendar, the period between the vernal equinoxes, is 365.25 days, while in fact it is almost 11 minutes shorter." No calendar has a length equal to the period between vernal equinoxes because that period is not an integer number of days. This sentence is just a mess from end to end. Jc3s5h (talk) 04:18, 4 October 2012 (UTC)


 * Of course the primary purpose was to "restore" the calendar to the Nicaean values, otherwise what was the purpose? Point taken re what was actually set down at Nicaea - I will revisit that at another time. However, the period of mean length of the year of 365.25 days is not mine. It was there before. I just tidied the wording up a bit by deleting repetitions of the same point.05:13, 4 October 2012 (UTC)


 * With respect to the vernal equinox falling on March 21 as it did near 325, there were two actions. One was to restore the equinox to March 21, by dropping the 10 days by making Thursday, 4 October 1582 Julian be followed by the first day of the Gregorian calendar, Friday, 15 October 1582 (or other dates in counties that adopted the new calendar later). The second action was, in every period of 400 years, to convert 3 leap years into common years. So the secular drift of the calendar with respect to the vernal equinox was, as far as the reformers could tell, eliminated. If they had reversed it they would have converted 6 leap years in each 400 year period to common years.


 * As for the sentence "The length of the Julian calendar, the period between the vernal equinoxes, is 365.25 days, while in fact it is almost 11 minutes shorter" the most glaring problem is that it does not say "mean length, it just says "length". Also, it would be better to say "Julian calendar year" because there are a number of lengths associated with a calendar, so it's best to be clear you're talking about the year length. Also, "Julian year" has a special meaning among astronomers, so it's best to specify calendar year. Finally, even Julius Caesar's advisers are thought to have known that the new mean calendar year length they advised was not exactly equal to the mean tropical year, so it would be more accurate to say that the mean length of the Julian calendar year was designed to better approximate the mean tropical year. Finally, the mean length of the tropical year changes over time and whether it is defined at the vernal equinox, autumnal equinox, or the modern definition. For the period 325 to 2012, the various varieties of tropical year are only different by a second or less, but some readers may be aware of the differences but not know the magnitude of the differences. Thus it would be best to cite a reliable source for "almost 11 minutes shorter" and the source should specify vernal equinox tropical year, and should specify that "almost eleven minutes" is equally applicable to 325 or 2012. Jc3s5h (talk) 12:44, 4 October 2012 (UTC)

Alternative Calendar
There is an alternative calendar to the Gregorian Calendar that is not listed on this wikipage's proposed reforms. It is called the Ehoah Globus Kalendar, with two other associated calendars that make it up - one for each hemisphere. There is no page on wikipedia on it, but it is a legitimate calendar that is out there and is worth noting.

65.92.205.173 (talk) 18:31, 15 March 2013 (UTC)


 * Stop promoting the calendar you created as hobby. Your IP address can be blocked and the website can be blacklisted. Jc3s5h (talk) 18:39, 15 March 2013 (UTC)


 * If I have got it right, it seems that on this particular cited website it is said (I quote) "the Gregorian calendar currently in major use is solar in time span, but does not revolve around the solar changes".
 * I must be stupid! I have no idea at all what this is supposed to mean given that the Gregorian calendar has in my own opinion always based very carefully upon the solar year action in all respects within our own world (it seems to myself that I do indeed have it right to suppose that this as here quoted from this website as here the title of which is mentioned on 15 March 2013 is not correct and indeed may be considered I am sorry to say as a complete nonsense?).
 * Peter Judge — Preceding unsigned comment added by 84.13.93.253 (talk) 17:58, 26 May 2013 (UTC)

table edited
"Difference between Gregorian and Julian calendar dates" table has been edited. If we reach a year which is a Julian leap year but not a Gregorian leap year (as in 1700,1800,1900,2100), the difference will grow by 1 day when the Gregorian calendar reaches March 1. This is because that year's Gregorian calendar omits February 29 (going directly from Feb. 28 to Mar. 1), but the Julian calendar, which is behind the Gregorian to begin with, has to go through February 29 to reach March 1. — Preceding unsigned comment added by 128.63.16.20 (talk) 19:42, 20 August 2013 (UTC)

INTRO very bad
The intro is terrible, muddled, real BAD. All the mathematical stuff, the detailed explanation regarding leap years, etc. should be transfered to core of the article (but it's there already!). The intro needs to be streamlined and reduced to half its present length. --Lubiesque (talk) 21:33, 28 August 2013 (UTC)

Chinese tradition of numbering the months
It seems that the article finds it odd that China keeps numbering the months. What's the problem? Isn't this better than giving stupid names? Moreover, weeks are also numbered, so Monday is simply called "weekday 1". It's really easy for learners. Besides, many children are confused and sometimes need to count in order to know which number is the month. This doesn't happen to Chinese people because of the more convenient system.--2.245.101.191 (talk) 23:22, 26 October 2013 (UTC)

Data for Map of countries using the Gregorian Calendar
I was thinking of doing a map (or someone else could beat me to it) showing what countries use the Gregorian calendar officially and what year it is in the countries that do not.

It is currently officially considered 2014 in every country of the world except for these:


 * Israel: 5773
 * Thailand, Sri Lanka: 2555
 * Nepal: 2069
 * Ethiopia: 2005
 * India, Cambodia: 1936
 * Saudi, Yemen, Kuwait, Bahrein, Emirates, Qatar, Oman: 1434
 * Bangladesh: 1419
 * Iran, Afghanistan: 1392
 * Myanmar: 1375
 * North Korea, Taiwan/ROC: 102
 * Japan: 25

These are the official calendars, note there are many other non-official and religious calendars in use in these and many other countries throughout the world. Til Eulenspiegel /talk/ 05:09, 2 January 2014 (UTC)


 * I think you're going to have to finesse the word "official". For example, it might be entirely reasonable to think that the United States Constitution assigns authority over calendars to the several states, so one might have to look to the statutes of the 50 states to decide which ones had "officially" adopted the Gregorian calendar.


 * Dogget wrote "The legal code of the United States does not specify an official national calendar" in the "Calendars" chapter of the Explanatory Supplement to the Astronomical Almanac (2nd ed.) Jc3s5h (talk) 16:46, 2 January 2014 (UTC)


 * The only calendar that has been used in all statutes anywhere in the US is the one that counts this as 2014, ie the Gregorian, no other has ever been used I'm pretty sure, so that's what I count as "official use" even if none of the statutes make this explicit. Til Eulenspiegel /talk/ 16:54, 2 January 2014 (UTC)


 * I agree that the Gregorian calendar is in general use for civil purposes in the US. I'm just saying that "official" might not be the right word. Jc3s5h (talk) 17:29, 2 January 2014 (UTC)


 * India does not use the Gregorian calendar officially? I see on the official Indian goverment site that the President of India, Shri Pranab Mukherjee, was very busy yesterday, 1 January 2014, receiving delegations after delegations of Indian federal and states government officials, business groups, etc in celebration of the passage to the new year: 2014.
 * In their case they do have a statute (actually a Constitutional provision too I think) making Shakta calendar official, even if they are de facto using Gregorian on their website, I would assume they are not being "forced" to do this by any identifiable agency. But since you gave a sounder reason for removing "accepted", I won't edit war on that minor point any more. Til Eulenspiegel /talk/ 17:34, 2 January 2014 (UTC)
 * Doesn't the United States use the concept of (I'm sure there's a technical name for it) incorporating the laws of preceding regime (i.e. Great Britain's laws as of 1776) unless and until they are superseded? After all, the rebelling states and the new federal government could not have instantly passed all the laws needed for governance in their first sessions. So Great Britain's law making the Gregorian Calendar official in 1752 is probably still in effect in the United States. Indefatigable (talk) 02:12, 4 January 2014 (UTC)
 * Yes, all the states except Louisiana have adopted English Common law through Reception statutes. However, they are worded in various ways. Not being a lawyer, I don't know if these reception statutes include only the common law, that is, decisions of courts, or also includes UK statutes. I understand that although 49 states have reception statutes, the federal government does not. Also, it is not clear if the Constitution gives the federal government the authority to regulate calendars; that might be considered a power reserved to the states.


 * One rationale the federal government might use is that unless there is a law or rule to the contrary, words have their ordinary meaning. Since people in the US ordinarily use the Gregorian calendar, dates with no calendar specified are in the Gregorian calendar because that's the calendar everybody uses. Jc3s5h (talk) 18:18, 4 January 2014 (UTC)


 * Okay, so I guess the category would be "official or de facto use"... Til Eulenspiegel /talk/ 14:08, 12 January 2014 (UTC)