Talk:Calendar

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
 * Like Mr Peters said, there's a bunch conflated in your question. At the level of precision you're talking about (adding and subtracting leap seconds and the like), calendars would most properly be considered to measure the relationship of the earth's position relative to the sun rather than 'time'. Given the importance of the sun to life on earth and its cycles to human anatomy, though, it's the only meaningful basis for measuring and organizing time for the foreseeable future. — Llywelyn II   21:02, 9 August 2023 (UTC)

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 Manual of Style (headings). &mdash; Joe Kress 19:01, Feb 13, 2005 (UTC)

"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. &mdash; Joe Kress 05:10, 2 Jun 2005 (UTC)

Other systems
The current treatment leaves out at least two important systems: calendars based on astronomical observation of stars and others based on seasonal observations. Both were common with early agricultural civilizations, with prominent survivals being the importance of Sirius to the Egyptian calendar and the Chinese solar term names. Michels (1949) could be used as a source by anyone with JSTOR access, but I'm sure there are others who have brought them up as well. — Llywelyn II   20:53, 9 August 2023 (UTC)

Etymology
When the new moon was first seen? — Llywelyn II   18:48, 12 August 2023 (UTC)

Historical section pretty bad
Oh, and the historical treatment omits East Asia and Mesoamerica. Also,
 * Nevertheless, the Roman calendar contained remnants of a very ancient pre-Etruscan 10-month solar year.[2]

The link is active and the archived link is dead/useless. Not sure how that even happens.

More important, what is this bit even trying to say? Lunation and the year—meaning seasons—were commonly used. The Pre-Etruscan Romans used the seasons. On a straight reading, there's no contradiction involved and no need to bring up the ancient-to-the-point-of-widely-disbelieved Roman legend in such a terse and broad section. (Granted, it's a modern Enc Brit source for the point but the claim is rather overstated. See Roman calendar for the widespread disagreement that this ever even existed.) On an implicit reading that an editor took the first sentence to mean lunar months and the solar year were always everywhere used together except in ancient Italy... well, that's just absurdly wrong. If anything, the Egyptians were the ones we should single out for specifically caring about the solar year and not giving much of a damn about how the moon fit in. The generous reading is that they thought—like many Romans themselves did—that the 10 months were still completely lunar, which could have meant the months rapidly cycle through the seasons owing to the mismatch. That would be different from the first part of the first part of the paragraph. It's also almost certainly wrong, though. (See Roman calendar: Either there was an unclaimed winter period between agricultural seasons to fill in the missed time or the 10 "months" weren't lunar at all but based on seasonal observations. Some Romans similarly misunderstood the three Egyptian seasons as a 3-Roman-month year, which helped them feel better about how ancient Egyptian culture claimed to be... and in fact was.)


 * The Roman calendar was reformed by Julius Caesar in 46 BC.[7] His "Julian" calendar was no longer dependent on the observation of the new moon, but followed an algorithm of introducing a leap day every four years. This created a dissociation of the calendar month from lunation.

Similarly, the Roman calendar was entirely divorced from actual observation of lunations for multiple centuries prior to the Julian reform, which was a shift in the mechanism of intercalation to agree with the long known and acted upon solar year of about 365¼ days. Just as important, it removed power from most other politicians to game the system to expand or shrink the year. (Apparently some governors still played games like feigning 14 month years to increase their tax hauls.)


 * Calendars in antiquity were lunisolar, depending on the introduction of intercalary months to align the solar and the lunar years. This was mostly based on observation, but there may have been early attempts to model the pattern of intercalation algorithmically...

This is similarly wrong. Lunar years aren't really a thing (we call 12 synodic months a "lunar year" just from rough analogy) and intercalation was heavily modeled, at least in Europe. I get that the ideas are weird and the math annoying. (All the moreso since ancient math was generally awful. The Romans themselves screwed up the first 36 years of the Julian system because they were adding the leap years inclusively... meaning every "fourth" year was actually every third. That required another 12 years of avoiding leap years to straighten out, meaning even the theoretically lucid Julian system wasn't actually in operation for its first 48 years.) The rhythm of prehistoric life was the seasons (almost entirely omitted from the historical treatment) frequently marked by animal behavior (fully omitted from the entire article) and the positions of major stars (ditto) or Jupiter (ditto). The history of accurate calendars has mostly been the game of trying to fit the lunar cycles into the solar year, meaning—at the time—the position of the sun against the fixed stars, which itself took time to figure out. The fights about computus—how exactly the spring solstice should fit into the months—might be inside baseball and unnecessary to do anything but link over to, but the octaeteris was a pretty big deal and the eclipse cycle was important early on, even if you don't want to get into the metonic cycle & the rest. — Llywelyn II   18:41, 12 August 2023 (UTC)