The first thing to understand is that the Maya used three different calendars. The first was the sacred calendar, or Tzolk'in, which lasted 260 days and then started over again, just as our 365-day calendar refreshes once it hits Dec. 31. This calendar was important for scheduling religious ceremonies.
The second calendar was the Haab', or secular calendar, which lasted 365 days but did not account for the extra quarter-day it takes the Earth to revolve around the sun. (The modern calendar accounts for this fraction by adding a day to February every four years, the reason we have leap years.) That means the calendar wandered a bit in relation to the seasons.
The final calendar was the Long Count Calendar — the recording method that has caused all of the doomsday brouhaha of 2012. On Dec. 21 (approximately), the calendar completes a major cycle, which has triggered doomsday fears and mystical rumors about the end of an age. [Full Coverage: The Mayan Apocalypse (Not)]
The Maya shared our culture's fascination with calendar mile-markers and would have likely considered the date important, Witschey told LiveScience. But they did not make any doomsday predictions about the date. The only two carvings ever found referring to the date depict contemporary kings and their predicted long-lasting legacies, Witschey said.
"Suppose I said to you that George Washington is so important that we will still consider him a revered national leader in the year 3000," Witschey said. "So now you've got the rollover of the zeros, you've got an important contemporaneous figure, and you're looking forward to the future." That's what the Mayan carvings are trying to accomplish, he said.
How the Long Count Calendar works
The Long Count Calendar may not predict doomsday, but it is good at covering long periods of time. Here's how it works: Dates are written out as five numbers separated by four periods, such as 13.0.0.0.0. (The ancient Maya represented these not with numerals, of course, but with their own hieroglyphs.)
This silkscreen shows dates in the Maya Long Count Calendar and a sacred calendar called the Tzolk'in. The silkscreen is based on carvings found in Quirigua, Guatemala. Credit: Andrea Dailey at Longwood University
The right-most position is called the k'in, which counts single days: 13.0.0.0.1, for example. The k'in counts up to 19 and then flips back to zero, with counting picked back up by the next position, the uinal. So 13.0.0.0.19 would become 13.0.0.1.0, much like a car odometer.
Each uinal is thus a block of 20 days. The k'in position then picks back up, counting up to that 20, which then gets added to the uinal. So the day after 13.0.0.1.0 would be 13.0.0.1.1 and then 13.0.0.1.2, all the way up to 13.0.0.1.19 and finally 13.0.0.2.0.
