Talk:Lunar calendar

Want to help write or improve articles about Time? Join WikiProject Time or visit the Time Portal for a list of articles that need improving.
—Yamara ✉ 22:07, 12 February 2008 (UTC)Reply

Question: If the Islamic calander can not be used to determine season then how do farmers sow the seeds in different Islamic countries.

Today I can understand they can use the Gregorian calendar because both are available, but how was the situation a centuries back?

Any idea?

In Egypt, the Egyptian (Coptic) solar calendar never stopped to be used by farmers, including muslim farmers. In the Middle, East both the Hebrew lunisolar calendar (derived from the Babilonian calendar) and the Julian solar calendar (derived from a mix up old the Roman lunisolar calendar and the Egyptian solar calendar) have alwasy been in commonin use beside the Islamic lunar calendar. Curiously, some Arab country traditionally use the Hebrew month names for naming the corresponding Julian months. 194.176.201.27 (talk) 11:39, 23 May 2008 (UTC)Reply

I have no idea what was actually used, but do have ideas about possible ways. For example one could reckon the same time of solar year to occur 11 days later next lunar year. If this puts that date into the next month of the lunar year one works it out as though the month had 30 days. About once every 21 lunar years it would need to b 12 days later rather than 11 days later.

Example:

  9 Safar 1426,  20 Safar 1427,  1 Rabi I 1428,
12 Rabi I 1429, 23 Rabi I 1430, 4 Rabi II 1431,
etc..

Karl 3 November 2005 (UT)

It has been suggested that the article Lunar year which is about a 12-month lunar year be merged with this article. I point out that a lunar calendar can in principle have a year of any number of months or no year at all. If the need to merge is very strong, I'd suggest placing its own contents in a section headed 'Lunar Year or 12 Month Lunar Year. Also the article links Lunar Year when mentioning the Islamic Calendar.

I'm happy for the articles to remain separate.

Karl Palmen 8 September 2006 09:10 UT

Are there any examples of a purely lunar calendar besides the Islamic calendar? The article would be greatly improved if we had some. If other examples don't exist, I'm not quite sure what the purpose of this article would be.--Pharos 18:28, 21 October 2007 (UTC)Reply

At least another example exist: the so-called "Lunar series" used in the Mayan calendrical system. That was a special-purpose calendar (possibly used to calculate lunar ellipses) composed of *six* lunar months. Adding this example would also be good to make the point that, in a lunar calendar, what really matters is the month length, while the "year" is just an arbitrary number of months collected together. This is opposed to the solar calendar, where what really matters is the duration of the year, and "months" are just arbitrary internal subdivision of the year (in fact, there are solar calendards with 19 19-days months, or 18 20-days months, but they all result in 365 and a quarted days per year). 194.176.201.24 (talk) 11:27, 23 May 2008 (UTC)Reply

The section titled "Old English 13-month *lunar* year" does not make sense, because that calendar acually was *not* a lunar, calendar but rather a *solar* calendar with an anusual internal subdivision (13 four-week periods plus 1 day, totalling *365* days!). And, once you have corrected the error and turned it to "Old English 13-month *solar* year", it doesn't belong in this article anymore... So, if everybody agrees (or I have no answers within a few days), I will correct that "lunar" intto "solar" and move the whole section in the "Solar calendar" article. 194.176.201.24 (talk) 11:29, 23 May 2008 (UTC)Reply

The only reason for not moving it would be if it was ever called a lunar year or its months called lunar months in the historical record, rightly or wrongly. However, the present section does not support that possibility. — Joe Kress (talk) 21:02, 24 May 2008 (UTC)Reply

Even if that was the case, in this article it would suffice to leave just a short note about the weird denomination, with a link to the proper article. 151.47.164.116 (talk) 12:41, 26 May 2008 (UTC)Reply

This is a good, informative article, but I think the "Length of the Lunar Month" section needs a little more clarification. I spent a good five minutes trying to figure out what exactly those numbers were supposed to mean, and how one could "use" them, and couldn't figure the latter out at all. My mother couldn't make heads or tails of it, either. We normal people need a little more explanation, please! 70.212.131.245 (talk) 20:20, 26 May 2008 (UTC)Reply

I removed the Dreamspell Calendar stuff, It is from a cranky non-notable site and not even a lunar calendar. It belongs in Calendar Reform if anywhere. Megalophias (talk) 00:59, 26 February 2009 (UTC)Reply

Deleted "It takes this long to complete a single revolution round the earth" from the "Length of the lunar month" section. The *sidereal* month is the time it takes the moon to complete a revolution around the earth (27.322 days); the *synodic* month is longer. A good explanation of this can be found at http://www.sumanasinc.com/webcontent/animations/content/sidereal.html . —Preceding unsigned comment added by Eggsyntax (talk • contribs) 22:27, 22 June 2009 (UTC)Reply

There is a link to a lunar calendar. It goes to a page that is selling a lunar calendar. For what it is worth, it is a beautiful calendar, but I don't see any other info on that page that contributes to this topic. — Preceding unsigned comment added by Hubie (talk • contribs) 18:28, 3 February 2011 (UTC)Reply

Removed it and another because they discuss lunar phases, rather than lunar calendars. — Joe Kress (talk) 06:40, 4 February 2011 (UTC)Reply

does any one know how old the lunar calendar is? — Preceding unsigned comment added by 50.45.97.62 (talk) 22:00, 24 February 2013 (UTC)Reply

There are many lunar calendars, which one are you asking about?

Aww no fair, there is nothing on the Inuit's lunar calendar? felinoel (talk) 17:18, 17 April 2013 (UTC)Reply

I note the partial reversion of my change wherein I had amended some of the "1 day off after X" figures; the explanatory note says "the exact amount depends on change of the synodic month value."

I appreciate that "round numbers" make for simpler explanations, but surely the main point of using rational number with small denominators as estimates for the synodic period is to enable simple calculations, and thus it is important for one to know when one must stop using such calculations. Accordingly the time limits should be rounded down rather than up. (To be fair, depending on time of day, one can be "out by a day" well before the limits given; perhaps that needs explanation too.)

Most synodic variation is not due to stochastic processes (where random variations may accumulate); on the contrary, most synodic variation is cyclic, primarily due to earth-sun orbital eccentricity (which mostly cancels out every year, and completely cancels out every 19 years) and moon-earth orbital eccentricity (which cancels out every 15 anomalistic months). The non-cyclic change over 70 years is about plus 13 milliseconds. See Lunar Periods.

Perhaps there is some other reason I have missed, but "change of the synodic month value" on its own does not seem like sufficient reason to assert that "off by one day after about 70 years" is a better error-limit than "off by one day after about 68 years".

Martin Kealey (talk) 13:03, 27 April 2013 (UTC)Reply

The calendar type selection in the upper right at the beginning of the article points to many calendars, including Gregorian and plenty Islamic calendars... yet strikingly, even this being lunar calendar article - the table is missing the link to Chinese calendar. — Preceding unsigned comment added by 79.233.82.242 (talk) 10:27, 9 March 2016 (UTC)Reply

The comment(s) below were originally left at Talk:Lunar calendar/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.

Last edited at 14:42, 17 January 2007 (UTC). Substituted at 22:37, 29 April 2016 (UTC)

Hello fellow Wikipedians,

I have just modified one external link on Lunar calendar. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:

• Added archive https://web.archive.org/web/20130809125949/http://phys.org/news/2013-07-scotland-lunar-calendar-stone-age-rethink.html to http://phys.org/news/2013-07-scotland-lunar-calendar-stone-age-rethink.html

When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.

This message was posted before February 2018. After February 2018, "External links modified" talk page sections are no longer generated or monitored by InternetArchiveBot. No special action is required regarding these talk page notices, other than regular verification using the archive tool instructions below. Editors have permission to delete these "External links modified" talk page sections if they want to de-clutter talk pages, but see the RfC before doing mass systematic removals. This message is updated dynamically through the template {{source check}} (last update: 5 June 2024).

• If you have discovered URLs which were erroneously considered dead by the bot, you can report them with this tool.
• If you found an error with any archives or the URLs themselves, you can fix them with this tool.

Cheers.—InternetArchiveBot (Report bug) 21:36, 27 May 2017 (UTC)Reply

I haven't made up my mind whether I think that that table in the section "Length of the lunar month" needs A) more work, or B) to go. It is somewhat informative, after one does a lot of thinking about what it actually says. It's sort of explained (if one doesn't obsess over "Continued fractions") in the text, although it could be clearer. The fractions presented come successively closer to the actual length, in days, of the synodic month. So one sets up some sort of cycle: one takes the number of days given in the numerator, and divides it into the number of months given in the denominator (devising some sequence of 30-day and 29-day months). And then after the time given, your calendar will be about one day off of the actual moon month.
Two other pieces of information might be worth presenting in the table:

• How many 30-day months and how many 29-day months does it need to make up each cycle (I've done some figuring, and it seems there's one correct answer in each case);
• Which way is your calendar a day off after the length of time, i.e., is your calendar running one day ahead of the actual moon month, or one day behind it.

Both of these can be worked out fairly easily with some basic high school algebra. And I'm thinking I could do that and make the table more informative/complicated. But I wonder if that would amount to original research. On the other hand, I wonder if someone did just that sort of work to devise the table to begin with. Uporządnicki (talk) 17:44, 20 May 2020 (UTC)Reply

I forgot to say, I'm hoping for people's comments. I'm kind of itching to expand that table, but I don't want to do a whole lot of work and have it validly removed. Uporządnicki (talk) 11:24, 21 May 2020 (UTC)Reply

About that point just added in a new "popular culture" section--I'm inclined to think that its relevance to the article is kind of a stretch, and its interest and appropriateness is kind of marginal. Thoughts? Uporządnicki (talk) 17:46, 28 May 2020 (UTC)Reply

Agreed. I am going to remove it for now, if anyone strongly disagrees with the removal they can go ahead and revert me. Greyjoy ^talk 05:11, 22 August 2020 (UTC)Reply

Several calendars named in that list of lunar calendars--including the Hebrew calendar, added a couple of days ago--are in fact lunisolar calendars. The article makes the distinction between the two, and really deals with lunar calendars AS OPPOSED to lunisolar ones. And there is an article on lunisolar calendars--where there is also a list that's rather longer than the one here. I'm inclined to the notion that the lunisolar calendars shouldn't be listed here; possibly, one might append to the list a note that they are listed elsewhere, with a link to the article on lunisolar ones. Uporządnicki (talk) 10:35, 24 June 2020 (UTC)Reply

Agreed, and I have just commented out more.

The Gezer page doesn't give much detail, but doesn't support being lunar, and the text of agricultural activities requires a lunisolar calendar.

The Igbo calendar page says it is linked to the seasons, with the new year starting in February. Lunisolar.

The Maori calendar is lunisolar: https://teara.govt.nz/en/maramataka-the-lunar-calendar/page-1

And the Yoruba page says "The calendar has a year beginning on the last moon of May or first moon of June of the Gregorian calendar." Lunisolar.

Mindstalk (talk) 19:31, 1 July 2023 (UTC)Reply

I just discovered that I made a major blunder in that table I expanded--the one about the 29- and 30-day months. When I said that this or that distribution would have the calendar a day ahead of, or behind the moon phases, it seems I had them exactly reversed. To illustrate, if you start on the full moon and make all your months 29 days long, after two months your calendar will show a new month about a day BEFORE the full moon. That is to say, your calendar will be AHEAD of the moon phases--not behind, as I had said. On the other hand, if you make all your months 30 days, then after two months the calendar will show a new month about a day AFTER the full moon; the calendar will be one day BEHIND the moon phases--not ahead, as I had said.
I think it was a language glitch in my head, not a math one. At some point, when I have more time, I'll go through the others in the table, redo the arithmetic, and double check that I have them all the right way round as far as "ahead of" and "behind." Uporządnicki (talk) 13:33, 3 October 2020 (UTC)Reply

All the calendars in the current version of this "lunar calendar" article are based on the phases of the moon (the synodic month of about 29.5 days, with about 12.37 synodic months per year).

Some sources mention a "lunar-stellar calendar", where each month begins when the moon passes the Pleiades (a sidereal month of about 27.3 days, with about 13.37 sidereal months per year), without regard for the moon phases.^[1] In other words, the day of the month in lunar-stellar calendars corresponds to the lunar station.

Should this article say a few words about such "lunar-stellar calendars", or is there some other more appropriate article about such calendars? --DavidCary (talk) 23:03, 6 October 2020 (UTC) --DavidCary (talk) 06:22, 12 December 2020 (UTC)Reply

Native american tribes have used a turtle’s back pattern of scales to establish the lunar calendar cycle. The peripheral scales surrounding the edge add up to 28, the number of days of a lunar cycle. The center of the shell comprises thirteen larger scales which represent the 13 moons of a year.^[1][2]

I've removed this section, as the veracity of these claims, in particular that "the center of the shell comprises thirteen larger scales which represent the 13 moons of a year" are extremely dubious. Although this section is cited, neither of these sources take into account that the lunar synodic month actually consists of 29.53 days, meaning this alleged lunar calendar fails to actually measure any lunar cycle with any accuracy, and that such a calendar of 13 months of 28 days actually more closely approximates the solar tropical year. So either the indigenous peoples who allegedly used this calendar completely failed in their purpose to measure lunar months, and somehow failed to observe the monthly shift between months and the lunar cycle, or these sources were unintentionally influenced by revisionists who were influenced in turn by Robert Graves (note that his "Celtic Tree Calendar", which also fails to be attested in the historical record and is widely used in neopagan and New Age circles, is also composed of 13 months of 28 days). The apparent total lack of any actual academic sources that can back up this "tortoise shell calendar" makes me suspect the latter is more likely. Midnight-Blue766 (talk) 20:26, 29 October 2020 (UTC)Reply

Doug Weller, I'm also hoping that the IP user whose edits you just reverted will see this.
I'm the guy who greatly expanded that table about various patterns of 29 and 30 months to attempt to keep with the actual synodic months. I calculated and added the data about how long (in years and days) each period is; I calculated and added the information about how many 30 day months and how many 29 day months there would need to be to make up the period; and where the original table had said on that after this much time you'd be about a day off, I figured out and stated whether that would be a day ahead or behind. I hope it was not original research; I did not come up with the original continuing fractions in the first place (I didn't know about it), and the rest was basic high school algebra.
That IP user figured out (not difficult) the time for the last pattern to fall one day off (assuming that the moon never changes its orbit--which of course it does). (S/he then went to rather a lot of trouble putting it in--getting it to format suitably; more on that in a bit.)
When I saw that, I had in mind to add a note to the table to the effect that the figure was hypothetical, assuming that the moon's orbit will stay constant over millennia--and in fact it wouldn't be accurate. Do you have any strong feelings on that?
And to the IP user--I hope you're seeing this. I, too, when I'm editing something with complicated formatting (and feeling my way around to do so), find myself editing many times before it comes out the way I had in mind (sometimes, before it comes out at all!). So I make MUCH use of the "Show preview" button. It's next to the "Publish changes" button. And it shows you, above the edit window, what your changes will look like if you save (publish) them. That way, I don't add a lot of edit history--some of which (at least for me) would have come out as garbled gibberish. When I get it more or less the way I had in mind, and it looks OK, THEN I publish the changes. Uporządnicki (talk) 18:53, 8 November 2020 (UTC)Reply

That Spanish "lunar calendar" for 2017 pictured at the top of the article might very well be for 2017, and it might even be Spanish--but it's not a lunar calendar, at least not in the sense described in the article. It is simply a schedule of the phases of the moon set against their dates on the standard Gregorian calendar. Uporządnicki (talk) 03:19, 12 November 2020 (UTC)Reply

I did some serious work concerning that table about patterns of months to accomplish an accurate lunar calendar; I substantially expanded the text explaining it all.
I was hoping for comments and/or improvements from others, and I said as much in my explanation of my edit, with the idea that it would show up on the Watchlist of anybody watching this article. Unfortunately, I then went back in and fixed a trivial spacing glitch in the edit I'd just worked on. I suppose because I did it just two minutes later, it's that trivial edit and not the substantial one that shows up on the Watchlist (or at least on mine). So here is my notification to anybody interested who is paying attention. Uporządnicki (talk) 13:45, 12 November 2020 (UTC)Reply

John Maynard Friedman, you have ostensibly provided a source (twice) for the length of time of one lunation--the CRC Handbook of Chemistry and Physics. But you've linked it not to an online edition of that publication, but to the Wikipedia article about it. So it's not really a linked reference. Also, you provided a page number. But the HCP comes out in editions over time. Unless each new edition always presents the same material on the same pages (possible, but I doubt it), then a page reference without a statement of the particular edition is kind of meaningless. Uporządnicki (talk) 12:50, 29 April 2021 (UTC)Reply

I cannot tell a lie. I just copied the citation verbatim from another article. I don't have access to a hard copy right now. So you would be entirely justified if you revert and replace with a better sources. It is hardly controversial data. --John Maynard Friedman (talk) 13:31, 29 April 2021 (UTC)Reply

John Maynard Friedman When your new comment came up on my Watch List, I was JUST about to come back and say that I saw where you got that. It came from the article about the lunar month, and it was added and "linked" in January 2016, by a User who made hundreds of edits in 2016 and hasn't done one since. I'll look around on line, at a time when I'm not supposed to be doing something else. Uporządnicki (talk) 13:38, 29 April 2021 (UTC)Reply

@AzseicsoK:, thanks, yes, that was it. I'll also have a search too. --John Maynard Friedman (talk) 16:06, 29 April 2021 (UTC)Reply

@AzseicsoK:, This analysis by Dr. Irv Bromberg (University of Toronto, Canada) would seem to suggest that the precision given is dangerous nonsense. So I don't think that we can say anything more than "about 29 days 12 hours 44 minutes and 3 seconds", => 29 45843⁄86400 or 29.526424 29.53059 days. --John Maynard Friedman (talk) 16:26, 29 April 2021 (UTC)Reply

First return on Google search is http://astropixels.com/ephemeris/moon/synodicmonth2001.html , which also gives this as the average answer for 2001 to 2100 and also gives a table showing how much each synodic month in 2001 varied from the mean. --John Maynard Friedman (talk) 16:55, 29 April 2021 (UTC)Reply

I notice a number of sites quoting 29.53109 ... --John Maynard Friedman (talk) 16:33, 29 April 2021 (UTC)Reply

But do they cite a source? AstroLynx (talk) 17:52, 29 April 2021 (UTC)Reply

How about p. 576 of this ref for this page and related calendar pages? Perhaps also a good reference for the length of the tropical year on other calendar pages. AstroLynx (talk) 16:29, 29 April 2021 (UTC)Reply

Which says Any particular phase cycle can vary from the mean by up to seven hours, making the precision even more dubious. But I think we can go with the line on page 577 that says For convenience, it is common to speak of a lunar year of twelve synodic months, or 354.36707 days. which gives a mean synodic month as 29.53059. Which is different yet again! But it is a more credible citation, perhaps? --John Maynard Friedman (talk) 16:44, 29 April 2021 (UTC)Reply

It comes from the companion to the Astronomical Almanac, the ultimate source for obtaining precise luni-solar coordinates. How much more credible do you want the source to be? The cited value is based on modern lunar ephemerides and is of course an average value computed over a very long time period. For the purpose of this page it will not be necessary to cite the value in full precision but anyone curious about more precise values can follow the link. AstroLynx (talk) 17:52, 29 April 2021 (UTC)Reply

Sorry, rhetorical question. Maybe to be more colloquial, I should have said "is it not more reliable?" (than any that give a different figure, or than Astropixels). Which is a roundabout way of saying I agree that this is the one we should use.

Since it was I who caused this ruckus, I will search for all instances (on en.wiki) of the stupidly precise figure and replace with 29.53059 and cite the Almanac as proposed by Astrolynx. --John Maynard Friedman (talk) 19:53, 29 April 2021 (UTC)Reply

  Done, mainly using this citation: The long-term average duration is 29.53059 days with up to seven hours variation about the mean in any given year.^[1] --John Maynard Friedman (talk) 22:59, 29 April 2021 (UTC)Reply

Great work but I have a minor quibble with the way how you phrased it. Your quote, following ESAA1992's definition of the length of a lunation on p. 576, appears to suggest that the length of the synodic month was derived from the length of the lunar year while it should be obvious that it is the other way around. Why not simply refer to p. 576 of ESAA1992? AstroLynx (talk) 09:08, 30 April 2021 (UTC)Reply

I struggled with that one too: my natural inclination is the same as yours - use the best figure per the Chapront-Touzé & Chapront formula. (I assume you are concerned, as I was, that multiplying by 12 then dividing again can introduce rounding errors.) But I concluded that we neither need nor want that degree of precision lest it tempt readers to treat the mean as an absolute. Why get exercised over parts of a minute when the real figure changes by many minutes between one month and the next. The figure on p577 is a practical one and readily verified.

But yes, in the Synodic month section specifically (but not elsewhere), it would be best to replicate the Chapront-Touzé & Chapront formula as per p576 the ESAA1992. I'll do that. --John Maynard Friedman (talk) 10:26, 30 April 2021 (UTC)Reply

OK for now, perhaps other editors will add their views on how to best phrase this. AstroLynx (talk) 10:31, 30 April 2021 (UTC)Reply

Meanwhile I have extended Lunar month#Synodic month thus:

A more precise figure may be derived for a specific synodic month using the lunar theory of Chapront-Touzé and Chapront (1988):
29.5305888531 +0.00000021621T − 3.64 x 10^-10 T² where T = (JD−2451545.0)/36525 and JD is the Julian day number.^[2] The duration of synodic months in ancient and medieval history is itself a topic of scholarly study.^[3]

--John Maynard Friedman (talk) 11:23, 30 April 2021 (UTC)Reply

Great, Chapront-Touzé & Chapront's 1988 paper giving details on the actual lunar ephemeris (commonly known as ELP 2000-85) is here. AstroLynx (talk) 12:03, 30 April 2021 (UTC)Reply

I have updated citation [2] above to fully credit Chapront-Touzé and Chapront. --John Maynard Friedman (talk) 17:53, 30 April 2021 (UTC)Reply

Reading the article on "Ancient and Medieval Values for the Mean Synodic Month" made me question my sloppy usage "long-term". 100 years? 1000 years? a million? a billion? Obviously not, but "modern" isn't great either. Can anyone suggest a better wording?

Chapront-Touzé & Chapront's paper (see above) is claimed to be valid for several thousands of years, so "long-term" would be a few thousand years. AstroLynx (talk) 12:03, 30 April 2021 (UTC)Reply

Yes, I can see that but my question is about the present day approximation of 29.53059: what are its limits? 1900 – 2100? 1500 – 2500? Even if I do the maths, it'll be OR without a citation. Anyone? --John Maynard Friedman (talk) 17:32, 30 April 2021 (UTC)Reply

Someone added a "citation needed" thingie to my edit about the length of a cycle in the tabular islamic calendar. But that comes from simple arithmetic. Uporządnicki (talk) 10:10, 12 May 2021 (UTC)Reply

Ah! Now I see, too, that someone also added a tag about Original Research to the entire section. I'm responsible for maybe a third to a half of the table that is the main point of that section. Initially I started examining it and playing with it because I (and at least one other person) were having trouble figuring out what it was all about. I set out to make it clearer, and then wound up expanding it considerably. I added several columns. (I also clarified and expanded what had been--as I saw it--a rather cryptic statement on the Tabular Islamic Calendar.) The data I added came from arithmetic, and a little very basic high school algebra. When I was working on it, I did worry about Original Research. I inquired somewhere (I don't remember if it was here or at some project page) whether that would intrude on OR territory. Someone directed me to some guideline that suggested that just doing some basic math on data available from somewhere is permissible. John Maynard Friedman, I think this might involve you, but I'm not sure. Uporządnicki (talk) 13:23, 12 May 2021 (UTC)Reply

Yes, there is an exception to the OR rule for basic arithmetic. What made me concerned was that it such a large section without independent sources. It is not a show stopper but it would certainly improve its credibility. You probably saw an earlier discussion about the length of a mean synodic month, where someone did some independent calculations to reach a figure that was unjustifiably precise, as the WP:RS source demonstrated. Hence the concern. If no-one else shares it, you can remove the tags. --John Maynard Friedman (talk) 14:00, 12 May 2021 (UTC)Reply

@AstroLynx:, do you have an opinion on this? --John Maynard Friedman (talk) 10:52, 13 May 2021 (UTC)Reply

The table demonstrates how increasingly accurate ratio's for the synodic month can be obtained from a continued-fractions analysis but the table does not explain the cycles commonly found in lunar or luni-solar calendars. The larger periods can perhaps be interesting for the makers of mechanical planetaria (Antikythera Mechanism, etc.) or astronomical clocks (Jens Olsen's World Clock, etc.) but for calendars they are too awkward. AstroLynx (talk) 13:16, 13 May 2021 (UTC)Reply

An IP editor has been trying to add Ethiopian calendar to the "See also", which is not unreasonable given that there are a number of calendars there already that are not lunar either. The problem, it seems to me, is that the See also list is too open-ended. I suspect what was intended originally, but not stated, is that it should be Lunisolar calendars, not just any old calendars. I suggest we change it accordingly? --John Maynard Friedman (talk) 11:00, 27 August 2021 (UTC)Reply

John Maynard Friedman Well, I do see that several of the calendars on the list--Chinese/Vietnamese, Hebrew--are in fact lunisolar, not pure lunar. (In most other cases, I just don't know.) But in fact, the Ethiopian calendar is not even lunisolar; it's solar. But your point is one that has been bugging me for a while. One problem is, purely lunar calendars are probably rare. (I suppose one obvious explanation is, it's far more important to know when it's going to be hot or snowy; when it's going to be rainy or dry, than to know when the moon is full.) If I wanted to make a "list" of purely lunar calendars, it would be a list of one; that one would be the Islamic calendar. So do we include individual lunisolar calendars on the list, on the thinking that they're a special kind of lunar? Or do we relegate those to the article on lunisolar? I propose removing the subsection on particular calendars and just listing the few articles on Islamic calendars (and any others that are GENUINELY lunar) among the other subjects (i.e., NOT particular calendars). Then list also THE article on the lunisolar calendars. I might "be bold" and do that, when I have time. Uporządnicki (talk) 12:47, 27 August 2021 (UTC)Reply

If I do that, I might also add one of those notes that only shows on the Edit page (if I can find, again, how you do that), advising people to add ONLY purely lunar calendars. Uporządnicki (talk) 12:48, 27 August 2021 (UTC)Reply

I agree. I completely fail to see the point of that see also list. IMO, the See also should list * lunisolar calendar (and if a reader wants to a for example, it is not hard to go there); and * solar calendar, ditto. That's it: two entries. So unless someone else has a good explanation in the next few days, off with its head.

For hidden notes, use less-than, shriek, hyphen hyphen [your words of wisdom] hyphen hyphen greater than. For example, <!-- NOW HEAR THIS! NOW HEAR THIS! --> (caps optional of course). --John Maynard Friedman (talk) 15:04, 27 August 2021 (UTC)Reply

A lunar year is 29.53 days only. A year is the time it takes for an object (as a planet) to orbit around a bigger one (as a star). A month is the time it takes for a smaller object (as a moon) to orbit around the object. One Earth year is 365.2422 days. One lunar year is 29.53 days. 2404:3C00:502F:4C80:C39:39A2:7F86:F4A9 (talk) 05:03, 29 August 2021 (UTC)Reply

Well you will need to persuade the International Astromical Union first. Meanwhile, Wikipedia will follow current worldwide convention. --John Maynard Friedman (talk) 12:10, 29 August 2021 (UTC)Reply

I can't tell if this IP User is trying to make some point about terminology--"month" versus "lunar year" (?)--or trying to DEFINE a specific time (29.53 days) for the month or orbit of the Moon--impossible, of course (although in fairness, I did read that somewhere or other once tried to pass a law to declare a neat value for pi).

But I wonder if s/he realizes that the time it takes for the Moon to go around the Earth is rather less than the time from one Full Moon to the next Full Moon. In fact, I think it's roughly two days less. The time s/he states, 29.53 days, is APPROXIMATELY the time from one Full Moon to the next. So it's rather more than this "lunar year" s/he talks about. Uporządnicki (talk) 12:42, 30 August 2021 (UTC)Reply

Oh, I've just now seen what this is about. Someone made an edit looking to "correct" some terminology. That edit was reverted. I guess someone was looking to validate that edit. Uporządnicki (talk) 13:40, 30 August 2021 (UTC)Reply

Yep, see also talk:Lunar month. What next, a proposal to measure this 'lunar year' as a number of 'lunar days' (wrt the planet) rather than counting in Terran days. Oh wait... --John Maynard Friedman (talk) 14:45, 30 August 2021 (UTC)Reply

The period of 12 lunations you're talking about is just mimicking the year of the Earth around the sun. Real lunar calendars don't have that. Also, an Earth month can't be divided into 29 or 30 days, it should be divided into about 28 nights. A night is similar to a day, but related to the moon. 2404:3C00:502F:4C80:75C8:D2CC:2F81:97B0 (talk) 04:41, 4 September 2021 (UTC)Reply

It seems that you want to reinvent the lunar calendar to what you feel it should be. Fair enough! Invent one and promulgate it. If it gains enough footing to warrant discussion and description in independent sources, it might get its own Wikipedia article. Uporządnicki (talk) 12:26, 4 September 2021 (UTC)Reply

In the intro, why is there so much emphasis for a Japanese calendar? like a whole paragraph. Did the Japanese calendar influence other nations? If any country ever deserves some emphasis in the intro. It should be China considering their lunar calendar heavily influenced East Asia in whole. Yet not even a single dedicated sentence was spared for China in the intro. Despite the Chinese calendar is undoubtedly the most important calendar CONSIDERING it is the "mother" that was adopted by many other Asian countries. It is probably the most influential calendar second to the Gregorian calendar. I added a single sentence stating that a number of East Asian countries strongly based their traditional lunar calendar on the original Chinese calendar.SoyDream888 (talk) 06:48, 20 January 2023 (UTC)Reply

Yes, you were correct about it being WP:UNDUE but for the wrong reason: there were two large paragraphs about lunisolar calendars in the lead that were undue because they were way off topic. Lunisolar calendars certainly need to be covered in the body but one or two sentences in the lead is all that WP:LEAD requires to summarise of one small section. --𝕁𝕄𝔽 (talk) 13:16, 20 January 2023 (UTC)Reply

• SoyDream888 has been blocked as a confirmed sock account.-- Ponyo^{bons mots} 22:07, 25 January 2023 (UTC)Reply

The Haida Calendar link redirects to the Haida page. However, it appears discussion of their lunar calendar has been removed from that page. Does anyone know why it was removed and if it now exists somewhere else? If it is merely gone, then the Haida Calendar should probably be deleted from the examples. 73.210.187.84 (talk) 14:31, 11 June 2023 (UTC)Reply

  Done as it hasn't appeared on the Haida people page on at least the last 18 months. --𝕁𝕄𝔽 (talk) 14:39, 11 June 2023 (UTC)Reply

Open to 𝕁𝕄𝔽. You do realize you've broken my heart, right? Uporządnicki (talk) 22:02, 6 January 2024 (UTC)Reply

 

The current lead image (Iran Kalender 1863 Linden-Museum.jpg) is an Iranian calendar so it seems probable that it is a Shia solar Hijri calendar rather than a Sunni lunar Hijri calendar. If so, then it is not appropriate for this article. Does anyone know for certain? 𝕁𝕄𝔽 (talk) 07:17, 19 April 2024 (UTC)Reply

Given that months in the lunar Hijri calendar are traditionally determined by actual observation, I think it almost certain that this is a solar calendar, so I have deleted it. The only slight doubt is that it could be a Tabular Islamic calendar but nothing in the file description suggests that it is. --𝕁𝕄𝔽 (talk) 12:17, 19 April 2024 (UTC)Reply