Astronomical Alignments at the Templo Mayor of Tenochtitlan, Mexico
In honor of the spring equinox, I’d like to share an interesting article by Ivan Šprajc that explores some theories regarding possible astronomical associations of the architecture of the Grand Temple. Mr. Šprajc is a Slovenian archaeoastronomy specialist with an interest in the ancient astronomical practices of the Aztec, Maya, and Teotihuacan peoples. This paper, “Astronomical Alignments at the Templo Mayor of Tenochtitlan, Mexico” is the result of the studies he conducted at the excavation site of the Huey Teocalli in Mexico City.
In this paper, Šprajc agrees with his predecessors Aveni, Calnek, Tichy, and Ponce de Leon that the Templo Mayor was indeed constructed to align with certain astrological phenomena and dates. This initial concept is partially based on some clues recorded by Mendieta that the feast of Tlacaxipehualiztli “fell when the sun was in the middle of Uchilobos [archaic Spanish spelling of Huitzilopochtli].”
The more traditional position, held by Aveni et al and supported by Leonardo López Luján in “The Offerings of the Templo Mayor of Tenochtitlan” (2006) holds that the festival’s beginning was marked by the perfect alignment of the sunrise between the two sanctuaries atop the Temple on the first day of the veintena according to Sahagun. To wit, Sahagun recorded that the festival month began on March 4/5 (depending on how you correct from the Julian to Gregorian calendar) and ended shortly after the vernal equinox.
Unlike his peers, Šprajc concludes that the festival of Xipe Totec was marked by the sun setting along the axis of the Teocalli. At that time, the sun would seem to vanish as it dropped into the V-shaped notch between the two shrines of Tlaloc and Huitzilopochtli. His conclusion partially stems from a slightly different measurement of the orientation of the temple than the other archaeologists, and his preference for Mendieta’s dating of the start and end of Tlacaxipehualiztli, which would start right around the vernal equinox and then end on about April 4th.
Who do I think is correct? I think the jury is still out. Both the sunrises and sunsets were marked by the priests with copal offerings and music, and both were involved in the flow of various festivals, so we know for sure that the scholars and clergy of Tenochtitlan assigned significance to both. Given the issue of varying estimates of how much the Templo Mayor has settled into the soft soil of the remains of Lake Texcoco, and differing theories on how much the structure has warped due to intentional destruction and pressure from the layering of Mexico City on top, and it becomes hard to present a bulletproof argument for either side.
Šprajc presents some additional interesting possibilities for alignments with Mount Tlamacas and Mount Tlaloc nearby, and a potential method of tracking the movement of the sun that possesses regular intervals of 20 days (matching an Aztec month) and 26 days (two Aztec weeks) that are intriguing. However, I generally consider Sahagun more reliable than Mendieta, as his research methods were among the best at the time, and modern study has tended to vindicate his records over those of historians working at a greater remove in time after the Conquest. There’s also the issue that Šprajc seems to be quite outnumbered when it comes to support for his alignment, and some of those who disagree with him, like Leonardo López Luján, have devoted decades of their lives to studying the Templo Mayor specifically. I’d also like to close with the possibility that everyone could be wrong — the tendency to see astronomical alignments under every rock and bush that were never intended by the people they’re studying has plagued archaeology for a very long time, and in the end, it could be the case here as well. Regardless, the debate is interesting and well worth reading, and the journal article contains a number of useful photographs and diagrams of deep within the layers of the Templo Mayor that are rewarding in and of themselves.
To download a full-text PDF copy of the journal article for free from the Inštitut za antropološke in prostorske študije (Institute of Anthropological and Spatial Studies), please click HERE. Alternatively, you can read it on-line at Issuu in simulated book format straight from your web browser by clicking HERE.
As a bonus, I’ve embedded a beautiful video recorded by Psydarketo below. It’s footage of the sun rising and aligning in the central doorway of the sanctuary atop the Mayan temple at Dzibilchaltun on March 20th, 2011 — last year’s spring equinox. It’s a similar technique to what I discussed above at the Templo Mayor, except that the sun is framed in the doorway rather than in the V-shaped space between twin sanctuaries. Close enough to help give a picture of how things would have looked in Tenochtitlan, and wonderful to watch in its own right.
Courtesy link to the original video at Psydarketo’s YouTube page.
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WorldCat Citation
Tlacatecco 
Interesting report…. Frey Sahagun wrote to a voluminuous degree factual information with the help of informant christian convert war survivors of the genocide upon his arrival to Tenochtitlan in 1529 (Some 10 years after contact). Sahagun taught Latin and History at the Colegio De Santa Cruz in Tlatelolco. First and for most, his assignment and duty along with 20 other Frayles sent by the Spanish crown at the time was to re-enforce the extremely busy clergy already in Anahuac. The mission and objective was to convert by any means necessary the demonic souls into a pacifist obedient christian workforce. The main objective in trying to achieve this was to demonize and or distorting every aspect of our ancestors scientific practices of measurement by imposing abstract theologian beliefs on the remaining ceremonial practices in an effort to win hearts and minds and quell uprisings by those who survived the onslaught of contact. Two years after his arrival the famous “Apparition of La Virgen de Guadalupe” at Tepeyac is made up in 1531 using European Art that looks nothing like our ancestors pre-contact codex writings. Hundreds of thousands of worriors and families would lay down their weapons and kneel after these lies were presented in the middle of a smallpox invested world. He is responsible for removing a small site meant for offering copal and imposed a cross in its place. I can go on but based on the testimony written about Frey Sahagun I can say that his writtings are tainted by historical bias to a lengthy extent. However, I would agree we need to take a critical look into both sound scientific researched Archeoastronomy and take an even more critiacl possition on most of Sahaguns interpretations. For the record, the well respected Leonardo López Luján and his fahter Alfredo Lopez Austin seem to be beyond just intrested in finding and exposing with great zeal the next archeo sacraficial site (sound familiar). Persnallly, I will side with the scientific word of an Archeoastronomer like Dr. Sprajc with the backing of Dr. Anthony Aveni any day.
-UNAM 132!
August 2, 2012 at 11:59 PM