Thursday, December 13, 2012

Did You Have a Vague Year?

The question can, but need not be, understood in an ironical fashion.  That word, vague, has a properly technical meaning applied to the year. Vague comes from the Latin, vagus, meaning “wandering,” “rambling,” and hence also “less than well defined.” Annus vagus is a wandering year. So what does that phrase mean?

It means a year of 365 days—unadjusted with leap days. When the formal calendar is structured like that, the simplest way to make it orderly is by assuming 12 months of 30 days and then five more days added. The ancient Egyptian calendar was structured like that. The Mayans had three different calendars: The Long Count (for which we have no name), the religious (called Tzol’kin), and the ordinary civil calendar (called Haab’), which was an annus vagus but made up of 18 months of 20 days to which were added five more (those five considered unlucky).

So what happens when one lives one’s life in a succession of vague years? Well, the actual year is then shorter than it really is, as marked by the sun, by 0.2442 days. That translates to 5 hours, 48 minutes, and 46 seconds. Therefore a festival, recurring on a fixed date of the vague calendar, begins nearly six hours earlier every year. If we put such a year in place today, Christmas would occur on November 25 in 2136. And so on. This shift in festivals—when the calendar isn’t accurate—caused humanity to introduce leap days or other adjustments.

The Mayan’s what with having three different calendars, of which the Long Count was very precise for long periods, adjusted to the seasonal shift not by introducing extra days but simply moving the date of the calendar. In the example above, Christmas would be nudged forward in time one day every fourth year to account for the drift—reminiscent of our leap year additions.

But what with this constant drift of the vague calendar backward in time (so that last year’s fixed date is earlier in the new vague year), eventually the calendar, having thus wandered off its moorings, would return to its beginning again. What goes around, comes around. And, of course, it does. So how long does that period take? It takes 1,508 vague years—and presto, Christmas is once more on December 25.

But did the Mayans know that? Did they have a real sense for the duration of the accurate, the tropical year? Evidently they did. At the Palenque archeological site near Chiapas, in Mexico, archeologists noted some inscriptions at an ancient temple, the Temple of the Cross, dates that were 1,508 years of their years apart. John Temple and Eric S. Thompson interpreted those dates as knowledge of the solar year (link). 1,508 times 365 is 550,420 days. And so is 1,507 times 365.2422, the length of the tropical year.

I bring this vital information as part of my series on the End of the World, projected by catastrophists to come on December 21 of this year. Other posts in this series are here and here. Now for the answer to that question. No, you did not have a vague year in 2012, not astronomically speaking. We hew close to the tropical these days. As for how 2012 felt, well that’s another matter.

1 comment:

  1. The Mayans may have been Central American brainiacs about calendar stuff, but they did not seem to know how important it was to have kids born on "12/12/12".

    I mean, you don't have codices that ramble on about so-and-so was born of "quetzal/quetzal/quetzal" now, do you?

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