Talk:Calendar

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[edit] Do calendars really measure time?

I think a lot of misconceptions about calendars arise from the idea that a calendar measures time, like a clock or like a ruler measures distance.

All known calendars work by naming days (This is the definition in the Nupedia article). As such, a calendar can not measure time more accurately than 1 day. Furthermore, the duration of the day is known to vary in time owing to change in Earth's rotation rate, so is not a good standard in time measurement.

A solar calendar may measure years, by virtue of the fact that its year runs close to the cycle of seasons, but more accurate measurement can be got from an ephemeris.

The year even when measured in SI seconds, varies in duration and so can not be considered a unit of the same time that measured by SI seconds.

That's not a misconception at all--a calendar does indeed measure time just like a

clock does, just not very precisely. That doesn't mean it's not a measurement. A measurement simply answers the question "how much"; one can answer precisely or vaguely. If you ask "How much sand in this bucket?", One can measure in "handfuls" just as easily as kilograms, and one is performing essentially the same function. Likewise, "How much time since I was born?" can be answered roughly in years with the help of a calendar, and in fact is a much more useful measurement for most purposes than an exact measurement in seconds: I'm over 1.2 billion seconds old; quick-- can I go into a bar? Run for president? --Lee Daniel Crocker

--- Mr. Crocker is confusing entities (e.g. length) with units (e.g. meter), organizational nomenclature (e.g. kilo-meter), and measuring devices (ruler, laser interferometer). A calendar itself, whether the paper thing on the wall or the rules and conventions used to make them, is NOT an instrument or system of time MEASUREMENT. Chalking up a mark each day is sufficiently similar to a clock (counting regular events) to call that a time measuring device: but that is a simple day count and not a calendar. A calendar is a convention on organizing time, dividing it, or tracking it if you like; but NOT "measuring" it. You might as well call the "minute" a system of time measurement, or a clock, or a calendar: and it is neither of these. So I propose as the initial definition for the article:

"A calendar is a system for organizing periods of time. Calendars generally use the day as the fundamental unit, and give a label (names or numbers) to each day. Days are organized into larger units which usually are repeated in cycles, often based on some natural cycle like month or year. These properties facilitate recording events or periods of history and planning future events."

       -- 20011221: Tom Peters

For more discussion on Calendars and Time measurement, you may join the E-mail list CALNDR-L at http://personal.ecu.edu/mccartyr/calndr-l.html


[edit] CALENDARS ARE CONSTRUCTS/SYSTEMIZATIONS/CONCEPTUALIZATIONS OF CIVIL TIME

Various calendars were created to conceptualize and give a semblance of order to the passage of time in reference to repeating events such as the changing of the seasons, the phases of the moon, the movements of Venus, the flooding of the Nile, etc. The orbiting of the earth about the sun is one of the most important repeating events for societies and civilizations for agricultural pursuits and animal husbandry, for example, not to mention preparing for temperature extremes, etc. Naming of calendrical units is not what a calendar is, but only a small part of the construct. Doc Rock 17:21, 18 October 2006 (UTC)


This terminology from the existing article seems less than ideal. "A pragmatic calendar is one that is based on observation; an example is the religious Islamic calendar."

How about calling it "observation based calendar" and get rid of the pragmatic terminology.

"A theoretical calendar is one that is based on a strict set of rules; an example is the Jewish calendar. Such a calendar is also referred to a rule-based or arithmetical calendar."

I thought a "theoretical calendar" was one proposed bu never used.

Let's just move away from those two term and go with Rule based and observation based.

-Paul Hill

I've never seen the term pragmatic calendar used to mean observation-based calendar outside the Nupedia article in which it appears. It may be the author's invention. The terms astronomical and observation-based have been used elsewhere and I have added them to the article.

The same applies to the addition of arithmetical and rule-based for theoretical calendars.

Karl Palmen

A calendar is not an scheme for "giving names to days and years". What a year is is defined by the calendar...for example, in a lunar calendar a year is something different than in a solar one.

I didn't write that that line, but actually I can't fault it. The primary purpose of most calendars is indeed to provide names for periods of time. Calendars generally do also define terms of common usage like "month", "week", and "year", and usually give alternate definitions for them that correspond in greater or lesser degree to other usages of those words which are not calendar-based (things like "mean sidereal year" exist independently of any calendar). But the purpose of those definitions is to provide a convenient way to label moments and/or periods of time in the past and future, to make it easier to record history and make long-range plans.

"Provide names to periods of time" that's a bit closer to it...my problem is, a year did not exist until a calendar that defined it did, so a calendar doesn't give a name to a year, creates it. But how do you measure those periods of time? A day is a pretty obvious thing, based on the movement of an astronomical object, the sun. The year is a bit more problematic, and you can only define it observing the constelations in the sky at sunset or sunrise. Thus my attempted definition. If you can do better, please be my guest, but I'm not going to leave that line as it is.

You could always look at it from the units-of-measurement point of view. Things like "hour", "second", "week", etc. are somewhat arbitrary products of definition, but just as we chose units like "pounds" to be useful for everyday life and commerce (imagine buying food from a grocer if your only units of weight were milligrams or tons), our choice of units for time was not entirely arbitrary. The day was such an obvious thing that it made sense for smaller units to evenly divide it. Likewise the cycle of seasons pre-dated any calendar, so it made sense for calendars to define the "year" unit of time measure in a way that made it convenient for knowing when to plant crops. So I wouldn't call calendars totally "arbitary", but I would say that they defined measurements of time that served the purposes of the prople that created them.

The various astronomical days, months and years really do exist; but the calendrical day and month and year do not. They are creations of the calendar, which approximate the astronomical periods in some ways. But they aren't just inaccurate measurements; to use the astronomical units would be wrong by the calendar. So these units have no existence without the calendar. -- SJK


[edit] From VfD

  • How to compute calendars - Article rehashes knowledge already available in detail on Gregorian calendar, Julian calendar, and Calendar itself, as well as being very centered on both of those calendars, but not giving details for either. If I have missed something, the missing content should be merged into one of those three and this page deleted; it does not provide additional value. Should the article instead be enhanced to encompass a "how to" guide for every calendar around, a lot of duplication would be neccessary (of the articles for the respective calendars) Eike 03:16, Feb 19, 2004 (UTC)
    • Info needs correcting, but merge any useful content with calendar and redirect -- Graham :) 12:01, 19 Feb 2004 (UTC)
    • Ditto. Elf 17:14, 19 Feb 2004 (UTC)
    • merge and redirect Rossami 04:22, 23 Feb 2004 (UTC)
    • If anyone wants to merge How to compute calendars into Calendar, they can access the non-redirected version from here.

[edit] Some reformatting needed?

and additions, especially where it just links to a main article. Lockeownzj00 06:25, 13 Feb 2005 (UTC)

If you're thinking of placing main article links within the headings, then don't. That is to be avoided according to the Wikipedia:Manual of Style (headings). — Joe Kress 19:01, Feb 13, 2005 (UTC)

[edit] "new" calendars

Should we say something about the phenomenon of people trying to build new calendars (such as http://en.wikibooks.org/wiki/Triangular_Earth_Calendar ) ? Is there a name for this, perhaps something like constructed calendar, analogous to constructed language ?

Some proposed calendars are at calendar reform. — Joe Kress 05:10, 2 Jun 2005 (UTC)

[edit] Asian Calendars

There is no information here on the main points someone would look for in a calendar article, which are the calendars in use today.

Japanese passports list birth dates that would make a westerner raise an eyebrow, and the Chinese calendar is misunderstood.

Perhaps before delving into the obscure, the present day topics should be tackled?

This article discusses calendars in general terms. For specific calendars see the category "Calendars" at the upper right hand corner of the article and especially its subcategory "Specific calendars" or even the List of calendars under "See also". In the last two you will find the Chinese calendar and Japanese calendar. Also see Chinese New Year. — Joe Kress 20:04, 4 August 2005 (UTC)

[edit] Improvement Drive

Time management is currently a candidate on WP:IDRIVE. Support it with your vote if you want to see this article improved to featured status.--Fenice 07:51, 5 January 2006 (UTC)

[edit] Moved from main article, by User:24.136.212.5

I would like an article titled AD and/or ADE and BCE if BCE exists.

The article would explain the difference between AD and ADE when placed after the number of a year. For example 2006 AD and 2006 ADE. What does the E stand for and when should or can it be used? Thanks, Marvin L Morrison

[edit] History behind the year starting in winter

Coming from the southern hemisphere the question has occurred to me of why 1 January was placed in the middle of the nothern hemisphere winter. It doesn't appear to be a question that has occurred to anyone anwhere on the internet. Would it be one for modern psychologists or were there cultural/religious/astronomical reasons for the winter solstice being chosen over the summer solstice? Did the Chinese start their year in winter? What about the Mayans? - Diceman 18:38, 24 March 2006 (UTC)

January 1 has no relation whatsoever to the winter solstice. Its placement relative to the seasons was the accidental result of converting the non-solar Roman Republican calendar into the Julian calendar in 46 BC. When Christianity adopted the Julian calendar as its own during the fourth century, it decided that the vernal equinox was on March 21. This caused January 1 to be 79 days earlier (80 in leap years)—there is no other significance to its placement. The difference between the Julian year and the tropical year then caused January 1 to drift later (closer to the vernal equinox). The Gregorian calendar corrected the drift in 1582 by placing the vernal equinox on March 19/20/21, depending on its leap year rules. The Chinese year begins roughly halfway between the winter solstice and the vernal equinox, but it is not a solar year. The Maya have two interrelated years: their 365-day haab year drifts relative to the seasons; their 260-day tzolkin year obviously has no relation whatsoever to the tropical year. — Joe Kress 09:49, 26 March 2006 (UTC)
I can't seem to communicate the concept of someone arbitrarily deciding where the year should start (I grew up in a place where new year's eve is in summer, and later on began to wonder why in the northern hemipshere where the calendar was invented, why they put summer in the middle of the year). I wonder where hunter-gatherer societies (that use traditional means of timekeeping) generally place the year. Someone on another page suggested a link to crop planting cycles, I assume that for agarian societies in colder climates, the work would begin in spring and end in autmn, with winter off, so winter would be the "end" of one year and the start of another. But I believe in mediterranean conditions crops are planted in autumn and harvested in spring because summer is too dry, so that doesn't quite add up. - Diceman 14:26, 26 March 2006 (UTC)
There is no reason that the beginning of the year should be logical, although many are. The Julian/Gregorian calendar is illogical, whereas the Hebrew calendar is logical, but as a result of history has two beginnings of the year in a single calendar, in spring and autumn, the months of Nisan and Tishri. Nisan (the first month) was the beginning of the year in the Torah (Pentateuch) when numbered months were used (with some Phonecian/Canaanite names), whereas Tishri (the seventh month) became the beginning if the year as result of the Babylonian captivity when the Jews adopted Babylonian names for their months. — Joe Kress 21:50, 26 March 2006 (UTC)

[edit] BEGINNING THE YEAR IN WINTER

An important element influencing the placement of January [the beginning of our calendar year] certainly must be the apparent movement of the sun along the ecliptic throughout the earth's trip in its orbit around the sun. This is because starting with the third day after the summer solstice the length of the day appears to shorten by about eight minutes every day until the winter solstice and it appears that the sun "may be going away." The return of the sun, i.e., the lengthening of the daylight period daily following the third day after the winter solstice, occasions great joy that light and warmth are returning to earth--a beginning of an annual renewal. That is why Christmas, three days after the winter solstice, got stuck in the calendar where it is on the 25th of December. The Norse celebrated the New Year at this time. January, moreover, is named for the two-faced god, Janus, who looks backward and forward. The end of the shortening of the daylight makes a logical start time for a new year--there are other rationales for other times as well. Doc Rock 17:35, 18 October 2006 (UTC)

[edit] Any Television Documentarys?

There are television documentarys about almost every subject a person can think of, (execpt to best of my knowlege - Valentine's Day). As anyone, ie PBS or the History Channel, done a made-for-tv documentary on the calendar? If not, then they should. There should be a least one television documentary on the history of the calendar.204.80.61.10 19:20, 5 December 2006 (UTC)Bennett Turk

[edit] Kurdish calendar

I've moved the following from the "currently used" calendar section: Kurdish calendar is a Solar calendar used among the Kurdish people. The Kurdish year begins on March 21st, at the time of vernal equinox. Kurdish calendar began 612 BC, when the Medes conquered Nineveh and Assyria, which marks and symbolizes the end of lowland tyranny. The year 2007 corresponds to the Kurdish year 2619. (Reference Kurdish calendar converter)

The only reference I can find for it is one that is associated with the already linked reference: http://www.kurdistanweb.org/kucs/project/calendar.html. There are maybe 2 other passing mentions of this calendar online. Other than that, there is no evidence of this calendar. If anyone else knows of other references, it would be worth creating a new article for the subject (under the category of "specific calendars"). It isn't notable enough to warrant a paragraph in the "currently used" section though. —The preceding unsigned comment was added by Nposs (talk • contribs) 23:59, 23 February 2007 (UTC).

It would be hard to get references for this as the Kurds have a mostly oral tradition. This makes it hard to get what you desire. However this does not mean that the kurdish calendar does not exist. In deed it does exist, and is well known among the kurds. Today is for example the first day of the year (20/3) 1 Jezhnan/Xakeléwe. Therefore i belive it is only just to mention the kurdish calendar in this encyclopedia. —Preceding unsigned comment added by 217.208.209.137 (talk) 12:13, 20 March 2008 (UTC)

[edit] hello wikipedians

I have to say .... I wold liked to see a quick referents table on when each calender was known to have bin calculated and taken in to use and so on. just saying it would be easier to visualize the time frame and also easier to remember :) thank you

[edit] Navigational bar 'Calendar systems'

The Dutch Wikipedia has a navigational bar about calendars: [1]. Would this be a good idea for the English version as well? Wiki-uk 12:49, 30 April 2007 (UTC)

Looks good. Used on over 20 pages. We should have one too. Robin Patterson 14:57, 30 April 2007 (UTC)
This was created on 27 June 2007: Template:Calendars Wiki-uk (talk) 17:56, 19 December 2007 (UTC)

[edit] Pragmatic and Theoretical Calendars

Does anyone know of any use of the terms pragmatic calendar for an astronomical calendar or theortetical calendar for an arithmetic calendar, independent of wikipedia? If not these terms should be deleted as original. Karl 12:17, 6 June 2007 (UTC)

I've removed the terminology of pragmatic and theoretical calendar on the grounds that they are original and other terms are used instead. You may restore them if you give good source independent of wikipedia for them. Karl 08:50, 12 June 2007 (UTC)

[edit] Calendar software

The calendar software section was getting a little spammy with a bunch of seemingly random additions [2]. Ironically it was linking to Mozilla Sunbird but not Outlook even though this is probably one of the most widely used calender programs. Instead I've linked to the Electronic calendar article and Calendar standards cat which covers most of what was linked to. The electronic calender article is a bit crap but it's the best we have. Ideally it would be better to link to a electronic calender standards article but we don't have one Nil Einne (talk) 07:26, 23 January 2008 (UTC)

[edit] Additional information to the article.

I feel that the part of the article on the Egyptian calendar should include the facts that their year was divided into three seasons of four months. I've seen a picture of the calendar taken off of an archeological site. One season was the harvest season, another was the flood season and the third I'm not sure of.

  This way of measuring may explain some human ages in the Bible.    For example, Abraham and Sarah were not 75 and 90 years old when Isaac was born.  She was about 25.   This would explain why she was concerned about not having a child, and why she was considered a great beauty by the Pharoah.

I don't have the time or the exact references, but they should be easy to obtain. —Preceding unsigned comment added by 209.244.188.179 (talk) 14:44, 27 January 2008 (UTC)

[edit] Easter

I'm genuinely confused about the assertions in the section about Easter Sunday:

[3]

Calculating the calendar of a previous year is a relatively easy matter when Easter Sunday is not included on the calendar. However, calculating for Easter Sunday is difficult because the calculation requires the knowledge of the full moon cycle. Easter Sunday is on the first Sunday after the first full moon after the Vernal Equinox according to the computus. So, this makes an additional calculation necessary on top of the normal calculation for January 1st and the calculation of whether or not the year is a leap year. There are only 14 different calendars when Easter Sunday is not involved. Each calendar is determined by the day of the week January 1st falls on and whether or not the year is a leap year. However, when Easter Sunday is included, there are quite a few different calendars.


The article asserts that calculating Easter Sunday results in "quite a few different calendars" than the 14 it asserts are all that exist by simply taking into account January 1 and leap days.

How?

Easter Sunday does not actually appear on any other day of the week but Sunday. It does not affect the seasons. Certain related holidays are "movable" depending on the date fixed for Easter, but they don't affect the calendar itself.

Perhaps there is a point to this section that simply eludes me, but if there is, it needs a source and some explanation.

Bikerbudmatt (talk) 17:26, 28 January 2008 (UTC)


Easter can occur on any Sunday from March 22 to April 25 inclusive, which is a range of 35 days. If the range were only 7 days, then the 14 calendars would suffice even if Easter were taken into account. The range of 35 days results in 70 calendars being required. Each of these 70 calendars can be specified by the date of Easter and whether the year is a leap year. The sequence of these 70 calendars is much more complicated than the sequence of the 14 calendars ignoring Easter. See Computus for more details. Karl (talk) 09:24, 29 January 2008 (UTC)

The Computus article was helpful...thank you. Perhaps what I am missing here, especially in the larger context of the Calendar article, is what is meant by "calendar" in this discussion. I am starting from the frame of reference of a Gregorian calendar. But the sequence of 70 possible calendars that are cited here seems to refer to placing the date of Easter itself, not to the overall Gregorian system. I would find it helpful as a reader to know this is what is meant here.

Thank you again for your patience in considering this...my interest is as a cleric who needs occasionally to explain items like this to interested congregants.

Bikerbudmatt (talk) 22:37, 29 January 2008 (UTC)

A look a the article showed to me that the section under discussion was badly placed. The previous sections dealt with different types of calendar system (e.g. solar calendar and lunar calendar) and this section dealt with different arrangements of dates in a single calendar system. I've reordered some of the sections including this one and added some clarification to it. Karl (talk) 09:21, 30 January 2008 (UTC)

Thanks, Karl; the reordering puts this section in context for me and addresses my concerns. Again, thanks for your patience and interest in working through this. Bikerbudmatt (talk) 14:45, 22 February 2008 (UTC)

[edit] Definition of Easter

The article has "Easter Sunday is on the first Sunday after the first full moon after the Vernal Equinox according to the computus.". That is misleading (also it has the problem that, worldwide, the Equinox instant occurs on two adjacent local dates).

At least in the British Calendar Act / Prayer Book tradition, "Vernal Equinox" is not used in the definition; the date is given as March 21st. I've not seen whether the Catholic (Clavius) wording uses Equinox or 21st; but their calculation must be based on the 21st.

Since AD 325 or thereabouts, Easter has depended not on the actual moon but on a calculated approximation.

A simple change to sort that out would be to use "Easter Sunday is nominally on the first Sunday after the first full moon after the Vernal Equinox, and can be calculated according to the computus.".

82.163.24.100 (talk) 11:12, 7 June 2008 (UTC)

[edit] Who uses which

I would propose a 500-day 10-month 50-week "metric"-year calendar in which to rewrite history and current worldwide time recokings and tell solar, lunisolar and solar calendars fkoff away with their inconsistency and half-astrological half-astronomical religion-centred purposes because, really, when one reads a historical date... How much sense does it makes? Which land used which calendar when? Reading the articles on Julian reform there are questions still unanswered...

What calendar did the Ottoman Empire used? I guess the Islamic Calendar but then, they had an Ottoman Calenadar at the 18th century which was a modified Julian, when most of the world had stopped using the Julian, so had they been used the standard Julian before? What calendar[s] does modern day Turkey and Greece use? What calendar was Hungary using before occupied by the Ottoman Empire in the year 1526, starting with a battle (29/8/1526)? Before it being formally annexed (1541?)? During its occupation and then iduring its anexation and then afterwards when it was freed from Ottoman control (1699?) Does Hungary uses the Gregorian calendar now?

Making dating meaningful is basic to make history a science of past-reckoning and not an art of realistic storytelling. In order to do that I guess a whole set of historians worldwide must study time in relation to a central, worldwide reckoning, that would mean killing off daylight saving times and stablishing a metric way to calculate time, much like the way space and mass are defined on things whose inconsistency, althought inevitable, is not pertinent to human simplicity as our complixity lays far away from their. But until such consesus is reached... Could more data be given on which region used which calendar when? I'm not Hungarian and probably the best and swiftest means I have to data about Ottoman presence on Hungary is from the English Wikipedia as the Spanish Wikipedia is not good enough right now and googling tends to redirect to Wikipedia anyway, otherwise giving useless results.Undead Herle King (talk) 15:34, 13 April 2008 (UTC)