Scientists Think They've Finally Figured Out How a Maya Calendar Works:
A cycle featured in Maya calendars has been a mystery pretty much since it was rediscovered and its deciphering began in the 1940s.
Covering a period of 819 days, the cycle is referred to simply as the 819-day count. The problem is that researchers couldn't match that 819 days up to anything.
But anthropologists John Linden and Victoria Bricker from Tulane University now think they've finally cracked the code. All they had to do was broaden their thinking, studying how the calendar worked over a period of not 819 days, but 45 years, and relate it to the time taken for a celestial object to appear to return to approximately the same point in the sky – what's referred to as the synodic period.
[...] "By increasing the calendar length to 20 periods of 819-days a pattern emerges in which the synodic periods of all the visible planets commensurate with station points in the larger 819-day calendar."
The Maya calendar is actually a complicated system made up of smaller calendars, developed centuries ago in pre-Columbian Mesoamerica. Of the component calendars, the 819-day count is the most baffling to modern anthropologists.
[...] There were other clues to suggest that the 819-day count was associated with the synodic periods of visible planets in the Solar System. The Maya had extremely accurate measurements of the synodic periods of the visible planets: Mercury, Venus, Mars, Jupiter, and Saturn.
However, the difficulty lay in trying to figure out how these synodic periods worked in the context of the 819-day count. Mercury is easy; it has a synodic period of 117 days, which fits into 819 days exactly seven times. But where did the rest of the planets fit?
It turns out that each of the visible planets has a synodic period that exactly matches a number of cycles of the 819-day count. Venus' synodic period is 585 days; that matches neatly with 7 counts of 819-days. Mars has a 780-day synodic period; that's exactly 20 counts of 819-days.
Jupiter and Saturn aren't left out, either. Jupiter's 399-day synodic period fits exactly 39 times into 19 counts; and Saturn's 378-day synodic period is a perfect match for 6 counts.
And there's even a compelling link with the 260-day calendar known as the Tzolkʼin. Twenty 819-day periods is a total of 16,380 days. If you multiply the Tzolk'in 63 times, you get 16,380 days. In fact, 16,380 is the smallest multiple that 260 and 819 have in common. So the two link up beautifully with the 20-cycle 819-day count laid out by Linden and Bricker.
[...] Any time historians are required to interpret significant measurements of ancient origins, they run the risk of reading too deeply and misattributing values. That's not to say Linden and Bricker's proposal is numerology dressed up as academia, though it is important to let science do its work and keep an eye out for critiques and rebuttals.
Still, the Maya calendar is far from a simple system based on basic astronomy. We shouldn't be at all surprised that the Maya's measure of the cosmos embraced such a great expanse of space and time.
Journal Reference:
Linden, J., & Bricker, V. (2023). The Maya 819-Day Count and Planetary Astronomy. Ancient Mesoamerica, 1-11. doi:10.1017/S0956536122000323
(Score: 0) by Anonymous Coward on Friday April 28, @05:34PM
Something something 819 days split into 20 sets of 45 celestial whatsits. Got it.
(Score: 0) by Anonymous Coward on Friday April 28, @07:56PM
To bad they got wiped out, or conquered, about 400-500 years ago. But at least now they can nail down the date according to their own calendar. The survivors can relish in the knowledge.
(Score: 4, Interesting) by maxwell demon on Friday April 28, @08:03PM (5 children)
The summary as is is pretty much a chaos (I'm pretty sure that 7 times 819 does not equal 585, for example, and 20 times 819 is not 780), and the article itself is paywalled. Of course any two integers have a least common multiple, so if you approximate the cycles by an integer number of days, you should find such a multiple.
Let's see if I can make sense of the the numbers given by the summary. Let's start with the given synodic periods, and calculate the lcm.
Let's compare this with the two special periods:
So the corresponding mutiples are:
Now some of the factors are already quite large, so I'm not sure I consider the numbers really convincing. Especially given that almost certainly the integer day numbers are approximations of the real periods, which is in particular significant for larger multiples (e.g. a 5% error, i.e. a deviation by 72 minutes, already gives more than a full day difference for 21 Mars periods).
The Tao of math: The numbers you can count are not the real numbers.
(Score: 2) by SomeRandomGeek on Friday April 28, @09:06PM (1 child)
It make sense from a certain point of view. The ancients were big on the idea that the heavens were eternal and unchanging, and the motion in them was cyclical. Eventually they come back to their start place.
This inevitably leads one to try to determine "How long is the whole cycle? Not just one star or planet, but how long until the whole thing resets?
If you are interested in this question, the interval 819 days is interesting, because all these other cycles seem related to it somehow, as opposed to every celestial object being on a completely unrelated cycle.
It is not an exact match, but it makes as much sense as epicycles in terms of trying to fit the heavens into our preconceived notions of what the heavens should be.
(Score: 4, Interesting) by maxwell demon on Saturday April 29, @04:28AM
Well, I've now noticed something that I didn't notice before: The other number, 260, is exactly 1/3 of Mars' period. And 819 is exactly 1/3 of the lcm of the periods of the first three planets. Conversely, the periods of all the planets are divisible by three (indeed, that's the gcd of all five periods).
Also something else: 4 times 819 is very close to 111 true synodic moon periods (using the approximation of 29.5 days actually makes that approximate agreement worse).
With those observations, the number seems a lot less arbitrary.
The Tao of math: The numbers you can count are not the real numbers.
(Score: 3, Interesting) by inertnet on Friday April 28, @09:34PM (2 children)
It would be interesting to know how they came up with this, because it would be almost impossible to figure out in one generation. It would even be hard in a single lifespan, while also making it the accepted standard.
(Score: 2) by hendrikboom on Saturday April 29, @03:03AM
Maybe they could do some mathematics?
(Score: 1) by khallow on Sunday April 30, @02:08PM
Synodic counts are no more than 780 days (a bit over two years) for any of the planets. Technically, with clear weather on the right days you could calculate all these numbers inside of three years to the nearest day or even fraction of an hour, if you're keeping careful track of the position of stars around the pole at the time of start and stop of the synodic period. But to get the accuracy described above, you need to run things out longer. But it could be done in a human lifetime.
The math then is in finding factorization of the overall synodic period into a neater form. They could have done the above period as 9*91*20, for example. There apparently is a common breakdown of days into groups of 9.
I think the craziest thing of this sort is the Antikythera mechanism [wikipedia.org] which I gather was originally thought of as a device for determining longitude. But which has since been determined to have been able to compute positions of planets and timing of eclipses with all kinds of specialized gears with weird, usually prime numbers of teeth. One of the gears in the device had 223 teeth.