Posted by: Johan Normark | November 4, 2010

2012: The Maya calendar correlation problem pt 2 – Thompson’s test

As shown in the last post on the issue of correlation between the Maya calendar(s) and the Christian calendar(s), there is not only a problem of correlating the Julian calendar and the various Maya calendars during the early Colonial period, there is also an issue of continuity between the Classic and Late Formative calendars and the ones known from the early Colonial period. One of the most important contributions to the correlation issue was delivered by Eric Thompson in his Commentary on the Dresden Codex (1972). The reason why the Dresden Codex is of major importance is that “it contains 260-Day almanacs, Year Bearer rituals, and Long Count dates. Prima facie, then, it should be a very rich source for bridging the Classic-Postcontact divide” (Aldana p 12).

Thompson discusses the methods used to correct the Venus Table that I mentioned in the previous post. He attempts to match predictions in the Table with historically reconstructed Venus periods. However, the proposed correction mechanisms for the Table do “not allow for both the early ‘base date’ [] of the Preface [Page 24 of the Codex] to correspond to an observable Venus event and for the much later corrected dates to also correspond to observable events” (p 12). The idea is that if a calendar correlation can explain the 16-day error between the ‘base date’ and later dates better than other correlations this might be the correct correlation. What Lounsbury did in 1983 was to take up Thompson’s implicit test since he accepted the idea that the date must be the intended base of the main table. Aldana writes that “it is no longer a question of why a discrepancy of 16 days might exist: it is now a question of what kind of date must have been given that it was 16 days from the event it was supposed to record. Lounsbury has now transformed Thompson’s implicit test into a formal problem for which he intends to provide the solution” (p 13).

Lounsbury plots the averaged error from through 104 haab against Thompson’s (and Teeple’s) correction mechanism. This leads up to a “zero” error day at the heliacal rise of Venus on 1 Ajaw 18 K’ayab (November 20 [JD] 934). The GMT correlation is the only one that does so and Lounsbury therefore believes it is correct.

Aldana shows how Lounsbury’s solutions find its way into other Mayanists’ works (particularly in the newer editions of Michael Coe’s The Maya and Anthony Aveni’s Skywatchers of Ancient Mexico). Coe and Lounsbury were colleagues at Yale as was Mary Miller. Linda Schele and Mary Miller produced the now famous book The Blood of Kings (1986). In this book they began using events mentioned in royal ritual texts with Gregorian dates along with the Long Count dates.

Aldana notices that a new genre of articles emerged that used reconstructed astronomical events in relation to inscribed dates in order to interpret the text and imagery. This can particularly be seen in Linda Schele’s later productions with other authors, such as Maya Cosmos (1993). This had the result, I may add, that the authors [Freidel, Schele, and Parker] discussed the timings of the Creation and other events in relation to Gregorian dates and astronomical constellations as well. Such speculations apparently had a profound effect on John Major Jenkins’ ideas of Galactic alignment as well as he began to focus on the “end” date instead, largely within a framework of Schele’s and Freidel’s cosmological interpretations of the Milky Way/World Tree, etc. In short, “Lounsbury’s proof of the correlation had been accepted and assimilated into the fabric of further research in the field” (p 18). It also, unintentionally, sparked the whole 2012 circus.

There is, however, a major problem with the original assumptions of Thompson and Lounsbury that David Kelley already pointed out in 1983. He was skeptical to the idea that the elaborate Venus Table was constructed with precise correction formulae and that the base of this table was set inaccurately by 15-20 days. That makes no sense. What Thompson has overlooked is that the discrepancy only exists because of the GMT correlation, the Dresden Codex itself does not state the discrepancy. The correction mechanism was “constructed to accommodate the predictions of the GMT” (p 19). Thompson made the mistake that the correction mechanism is “independent of the calendar correlation he used to produce it” (p 19).

There are, however, non-astronomical formulations of the GMT as well. I will discuss them in another post (I believe there will be more than three posts on Aldana’s important article). To be continued…



  1. Dear Johan,

    Very impressive amount of information that you have compiled here. I found it while trying to find a copy of David H. Kelley’s work concerning the correlation issue. Then, I see the name of Alanda and his work, but I did not see a link for his correlation essay; I’m wondering if this is a PDF or if your talking about the recent book artical of his.

    In any case I just recently sent Aldana a link to my latest webpage “2012 Summary,” from my website of

    I don’t no yet exactly what he thought of it or even if he has yet read it. However, I know when he does that he is going to accuse me of having allot of “tool marks,” which is reference to astronomy that cannot be had in our modern times without the help of astronomical software and the like. But that’s exactly the problem that modern science doesn’t like to deal with. The problem is that the ancients saw a different sky then we do – city lights or none! For this reason, the greatest of some scientific minds cannot conceive of the kinds of perceptions that were taking place within certain times such as that which is found with Mesoamerica.

    With this inability, science sets out to measure the standard of human perception and ability as is seen fit by modern standards. This practically amounts to insisting that if we cannot see stars because of our city lights, then that means that the ancients could not either. I have heard various statements that would imply just such a scenario: Like if modern city builders do not align our houses to astronomical coordinate points (which by default they do) then why would the Maya. I have heard this kind of thing, and I think you know what I’m talking about. Its like saying if we don’t base or societies on star worship, than why would the Maya, when there is plenty of proof for it in Babylonian Culture (of course!) but when it comes to the Maya you’ll need a little bit more of an understanding about constellations to get it all together.

    But we don’t have to get it together when there is so much missing, which allows us to constantly play the ‘there is no proof card’…THERE IS PLENTY OF PROOF WHEN WE KNOW HOW TO LOOK FOR IT. That should be applied to the whole question of Correction Dates in Mesoamerican Chronology as well as to the stellar constellations. My website will point out deliberately forgotten pieces of information to postpone the whole exploration of intercalery dates in Mesoamerica. If you get the chance I’m sure you will enjoy reading it. In any case, despite everything you could ever write on this website, I am bound to see here as in all arguments concerning the GMT correlation a lack of attention to this whole “Correction Issue,”(although you did mention it in some manner) and I think its done out of a needed sense of sophistication that would assume that any good calendar would not need such things – but the reality is to be that all solar calendars have them; and specifically because they are needed.

  2. It is his article in an edited volume I refer to. The whole coverage of his article can be found here:

    I do not think Aldana emphasizes the city light problem to any significant degree. His major objection is that too much archaeoastronomy is based upon what the sky looked liked at certain dates recorded in inscriptions. These are all dependent on the GMT or GMT+2. As I will elaborate in a future post on Aldana’s work on astronumerology I agree with him that it is still best to maintain the Long Count dates rather than translate them to Christian dates. As I mentioned in my recent post on Aveni’s research on Maya numerology, the recorded dates rather emphasize durations or intervals. These intervals can be subdivided by known celestial periodicities. These can still be studied without the correlation issue affecting it.


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