Talk:Gregorian calendar

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)

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.