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Math Space Science

Scientists Finally Solved the Mystery of How the Mayan Calendar Works (popularmechanics.com) 97

An anonymous reader quotes a report from Popular Mechanics: The Mayan calendar's 819-day cycle has confounded scholars for decades, but new research shows how it matches up to planetary cycles over a 45-year span. That's a much broader view of the tricky calendar than anyone previously tried to take. In a study published in the journal Ancient Mesoamerica, two Tulane University scholars highlighted how researchers never could quite explain the 819-day count calendar until they broadened their view.

"Although prior research has sought to show planetary connections for the 819-day count, its four-part, color-directional scheme is too short to fit well with the synodic periods of visible planets," the study authors write. "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." That means the Mayans took a 45-year view of planetary alignment and coded it into a calendar that has left modern scholars scratching their heads in wonder.

Mercury was always the starting point for the tricky timeline because its synodic period -- 117 days -- matches nicely into 819. From there, though, we need to start extrapolating out the 819 number, and if you chart 20 cycles of 819, you can fit every key planet into the mix. And Mars may be the kicker for the overall length. With a 780-day synodic period, 21 periods match exactly to 16,380, or 20 cycles of 819. Venus needs seven periods to match five 819-day counts, Saturn has 13 periods to fit with six 819-day counts, and Jupiter 39 periods to hit 19 819-counts.
"Rather than limit their focus to any one planet," the authors write, "the Maya astronomers who created the 819-day count envisioned it as a larger calendar system that could be used for predictions of all the visible planet's synod periods, as well as commensuration points with their cycles in the Tzolk'in and Calendar Round."
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Scientists Finally Solved the Mystery of How the Mayan Calendar Works

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  • by Narcocide ( 102829 ) on Thursday April 20, 2023 @10:55PM (#63466228) Homepage

    Does this mean they finally figured out when the world is going to end?

    • You start counting cycles of 819 and tell us when it ends.

    • My calendar ends on December 31st, 2023. By the "logic" applied to the Mayan calendar, we all have just months to live because the world is going to end soon.

    • December 2012 was a new calendar cycle. And if you look back a whole bunch of shit started happening more frequently since. More frequently severe weather. More frequent mass shooting events. More frequent political scandal after scandal. More frequent riots. More mass brainwashing on social media. They very well may have gotten it right. 2013 onward is a stark contrast to 2012 and before. In the 90s that blue dress was all the scandal for over a year. Today that would be yesterdays news after 2 days. Somet
    • It comes down to conflicting religions for using the bible as source materals. The original authors of the bible were Jewish, a celebrate the 7th day of creation from biblical book of Genesis on the day currently called Saturday. From this interpretation, Saturday is in fact the last day of the week, as it is the 7th day, and the day of rest and worship.

      Unfortunately, Christianity shifted their day of worship to the day of the week where Christ was raised from the dead (or more to the point, discovered to
  • 1140 x 819 (Score:5, Interesting)

    by superposed ( 308216 ) on Friday April 21, 2023 @12:13AM (#63466288)

    Expanding to 20 cycles of 819 days instead of 4 is interesting, but only Mercury, Venus and Mars will be in the same position at the end of 20 cycles as they were at the start. Mercury will repeat 7 times per cycle, Venus will repeat 28 times in 20 cycles and Mars will repeat 21 tiems in 20 cycles.

    But Saturn will repeat 43 1/3 times in 20 cycles and Jupiter will repeat 41 1/19 times. That's not very satisfying.

    It seems like if the Mayans really knew these cycles then they probably had a calendar in mind that was 1,140 cycles of 819 days each (about 2,556 years). After 1,140 cycles, all the planets would be back exactly where they started. During that time, Mercury would repeat exactly 7,980 times, Venus would repeat 1,596 times, Mars would repeat 1,197 times, Saturn would repeat 2,470 times and Jupiter would repeat 2,340 times.

    • Yuga (Score:2, Insightful)

      by elcor ( 4519045 )
      Could this be connected to Vedic yugas?
    • Re: 1140 x 819 (Score:4, Interesting)

      by superposed ( 308216 ) on Friday April 21, 2023 @12:53AM (#63466326)

      Another way to look at this is that the Mayans would probably have nested cycles for the return of the planets.

      According to the numbers in the article, if you start counting when all the visible planets are in a particularly interesting alignment, then Mercury and Venus will be back in the same positions after 5 cycles of 819 days, and Mercury, Venus and Mars will all be back in position every 20 cycles.

      Then every 60 cycles (3 sets of 20), Saturn will be back in position with the first three, and every 380 cycles (19 sets of 20) Jupiter will be back with the first three.

      Finally, every 1,140 cycles (3 x 19 sets of 20), all five will be back to the original alignment.

    • I don't know if Mayans were interested in having a full cycle in about 45 years. Seems sort of long for the average person.

      Maybe it has to do with the average lifespan of a humans those days? Or at least average lifespan of the royalty at that time if the average Mayan has a lesser lifespan?

      I can see the royalty thinking in terms of things they want to achieve within their lifespans and using that long span calender for milestones on objectives.

      • Lifespan averages are misleading. Child and infant mortality greatly skew the average; after surviving a few years, people were likely to live quite a long time, probably as long as they did before antibiotics; not long ago.

    • Could be simply that Jupiter and Saturn don't really move much. Not saying you wouldn't noticing them moving over say 20 years but when compared to like Mercury its something a child would even notice. In my mind you would either have to have really detailed drawings each night of the stars to be able to calculate this or do it only on brute force memory. In either case I am betting Jupiter and Saturn must come up somewhere in the mythos. You can't have that many board people looking to the stars evey ni

      • by ceoyoyo ( 59147 )

        Jupiter makes almost two complete orbits in 20 years, and Saturn about 2/3s of one. I hope you'd notice that.

        You could easily be off by a few days measuring their orbital period by naked eye though.

      • You don't actually have to observe 20 or 1140 full 819-day cycles to figure this out. You just have to know the synodic period for each planet (e.g., Jupiter reaches its closest point to some peak every 389 days). Once you have that, you just have to noodle around looking for common factors among the planets.

        That seems to be the significance of the 819 days. It's a base unit for all these cycles. Pretty impressive combination of observation and math.

    • I like your maths...and the way that you innocently proved that scientists in the article got "participation trophies", not graduation degrees, because they could not do their maths.

      • Scientists and mathematicians are lame - just ask all the hard questions on Slashdot, there will be someone here who can answer with the utmost confidence from their mom's basement.

    • by jonadab ( 583620 )
      I think we're reaching here. Mathematically speaking, if you take the lengths of all the cycles, prime factor them, and multiply together the minimal set of prime factors that's a strict superset of all of the cycles, then *of course* you're going to get a cycle length that matches up with all of them. It's fairly trivial to prove, mathematically, that this technique will work for any set of cycles of integer length. Proving that you can make the part-of-a-day fudge-factors work out for non-integer-lengt
      • I wondered about that. The periodicity of the planets does seem to be the reason for the 819 day calendar, which I guess was the main point of the article.

        But presumably if the planets had different periods there'd be some other number that worked equally well (I think that's your point). So it's no miracle that these patterns exist and maybe no miracle that the Mayan's spotted them.

        That's probably especially true if you allow for the fact that the Mayans probably only knew the synodic periods to within a d

        • by jonadab ( 583620 )
          > The periodicity of the planets does seem to be the reason for the 819 day
          > calendar, which I guess was the main point of the article.

          Yes, but it may be based only on the first three (excluding Earth). The fact that there exist integers N and M such that N cycles lines up for Jupiter and M cycles lines up for Saturn, should not surprise anyone and does not prove that the Mayans took those planets into consideration. If Jupiter and Saturn had different orbital periods, it would still be true, N and
  • by Required Snark ( 1702878 ) on Friday April 21, 2023 @12:48AM (#63466324)
    31.13.3 Converting from the Mayan Calendar [gnu.org]

    You can enter dates into your calendar using Mayan notation. And it will auto-complete the Maya date names because EMACS!

  • Would have been nice if they figured this out before the world ended.

  • by greytree ( 7124971 ) on Friday April 21, 2023 @06:59AM (#63466656)
    Can they now investigate why some online calendars and date selectors start the week on SUNDAY?

    Do the words WEEK END have some different meaning for the programmers who do this?
    • Maybe they believed Weekends should be like Bookends, one on each side? :)
    • Can they now investigate why some online calendars and date selectors start the week on SUNDAY? Do the words WEEK END have some different meaning for the programmers who do this?

      Obviously they are products of the Satanic Temple reversing the Genesis account.

    • It's those damn money worshipers e.g. the Mega Church types ... not the Satanists. Many pay calendars start the week on Sunday rather than Monday,l
    • Can they now investigate why some online calendars and date selectors start the week on SUNDAY? Do the words WEEK END have some different meaning for the programmers who do this?

      Hmm, I don't know. Makes sense to me but I am a programmer... If I told you to put a pencil in front of you and asked you to point at the end (however many there are), would you point to just 1 or would there be 2? Why can't the 'beginning' of something also be an 'end'? Just because it is measuring time instead of something more physical doesn't mean it doesn't have 2 edges and I'm fine calling those edges 'ends'.

    • Because what we designate "Sunday", legacy systems designate "day one" and use 1-based indexing.

    • by jonadab ( 583620 )
      Sunday was the first day of the week in most human cultures for most of history, and still is for a bit over half of the world's population. Monday-first calendars originated in the modern era, in Europe, in a business context, originally solely for use by businesses that were closes on Saturday and Sunday. Their widespread adoption postdates that of cheap wood-pulp-based paper in the late nineteenth and early twentieth century. Their use didn't become universal, even in Europe, for a couple more decades
      • So do a little experiment: Ask 100 people what day their week starts on.

        And come back to us here.
      • For the last 500+ years, those Yurpeans were almost all - more or less - Christians.

        On what day did their fairy tales tell them that God rested after creating the universe, and on what day of the week did their fairy tales tell them to rest?
    • Do the words WEEK END have some different meaning for the programmers who do this?

      A piece of string has two ends and, if you think of a week like that starting on sunday and ending on saturday then both ends are at the weekend...which is actually one word not two.

      • How many people that you know get up on Sunday morning and say "Okay, let's start the week" ?
        You are being disingenuous.

        Some countries do start their week on a Sunday, due to different religious fairy tales.
        But not any English-speaking or European ones I can think of.
        • Some countries do start their week on a Sunday, due to different religious fairy tales. But not any English-speaking or European ones I can think of.

          The first day of the week in the US [timeanddate.com] is officially Sunday and while you might disagree that they are English-speaking Canada also has Sunday as the first day.

          • Yes, but how many people in the US and Canada think that ?

            Again, how many people that you know get up on Sunday morning and say "Okay, let's start the week" ?

            Or, conversely, how many think the weekend ends on Saturday night ?
            • Again, how many people that you know get up on Sunday morning and say "Okay, let's start the week" ?

              I don't know any but I also do not know any that get up on Monday and say "let's start the week" either so that is not really convincing one way or the other. Generally speaking, the "first day of the week" is a rather meaningless concept unless you are working on a diary or calendar display so really it is down to just some official definition either based on the start of the current work week (which is Monday) or the historical start of the week dating back to the late Roman empire (which is Sunday). Nei

              • "Generally speaking, the "first day of the week" is a rather meaningless concept".
                Nope.
                Ask people, see what they say.

                Monday is what the vast majority of people in the US and Europe expect, so it is what websites should show us.
    • I work for a large engineering company that makes use of the "9/80" schedule. One week we work 9-hour days Mon-Thu, then an 8-hour day on Friday. The following week we work 9-hour days Mon-Thu and have Friday off - so 80 hours every two weeks with every other Friday off. Most people like it, but it's based on a fiction: In order to not be required to pay overtime the first (44-hour) week, they tell us our week ends "mid-shift on Friday" - so the next week begins 1/2 hour before my lunchtime on Friday! I don
  • Are tables beyond the capabilities of the Popular Mechanics writers? After battling filters:
    | ...... | Modern | Aztect | ....... |
    | Planet | Sideral| Sideral * Periods = Days = N * 819
    |
    | Mercury| 116 | 117 * 7 = 819 = 1 * 819
    | Venus | 584 | 585 * 7 = 4095 = 5 * 819
    | Earth
    | Mars | 780 | 780 * 21 = 16380 = 20 * 819
    | Jupiter| 399 | 399 * 39 = 15561 = 19 * 819
    | Saturn | 378 | 378 * 13 = 4914 = 6 * 819
  • The simplest and most feasible answer is that the Mayan calendar's cycles were/are actually incorrect, and modern day scholars are just trying to beat it into "correctness" by adding fudge factors.

    Of course, this is politically incorrect and unpopular, as a subset of humans seem to think that primitive civilizatoins had it "all figured out". Maybe that belief is wrong too.

  • If 45 years was considered a good average lifetime back then, perhaps the calendar was an "end of your life" as well as "end of the world" marker...

  • i only hope they don't reveal they've discovered the world is ending again! i'm getting tired of the world ending all the time!
  • Me: How does Mayan calendar work?
    ChatGPT: The Long Count, Tzolkin, and Haab calendars were used together to create a complex and highly accurate system of timekeeping that was essential to Mayan religious, social, and economic life. The system was able to track astronomical events such as the cycles of the moon, the movements of the planets, and the solstices and equinoxes, with a high degree of precision.

  • How does it differ from the 20 x 819-day cycles on page 142 of the Abstract Book of the 26th SEAC Conference at Graz, 2018?

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