[Aztlan] E-Groups

Fri Feb 22 15:29:19 CST 2008

Bob Hall's "puzzle," that the Waxactun E-group has been understood to  
mark the solstices and equinoxes while the stelae dates mark the days  
of nadir passage at that latitude, reflects a most important insight.  
He is also correct in noting that nadir passage is rarely mentioned  
in the literature on the ancient Maya; as he correctly states in a  
later message, "the cosmological significance of nadir passage  
deserves more attention than it has gotten."

In 2005-2006, I conducted a study of the sun at the eastern horizon  
at Chocola, a Middle Preclassic site on the Pacific piedmont,  
situated at 14.610° N, in the narrow latitudinal band where, as at  
Izapa and Copan, the long interval between the two solar zenith  
passages is 260 days. Zenith passages occur on April 30 and August 13  
(the start of the current Maya era, 13.0.0.0.0 4 Ajaw 8 Kumk'u, is  
August 13, 3114 BC in the Gregorian calendar); nadir passages occur  
on February 9 and November 1.

I presented my findings at the Symposium on "New Perspectives on  
Ancient Maya Astronomy" at the 2007 meeting of the Society for  
American Archaeology. One of the conclusions of that paper (presented  
as a hypothesis in the absence of field testing) is that the Waxactun  
E-group could have been used by ancient Maya astronomers to mark  
sunrises on the days of zenith and nadir passage as well as the  
sunrises on the solstices and equinoxes.

Examining Ricketson's plan view of the prototype Waxactun E-group  
(Ricketson and Ricketson 1937:Fig. 197), the azimuth of a line from  
the stairs of E-VII-sub across the center of the north building (E-1)  
is 71.5°, very close to the azimuth of zenith passage at a flat  
horizon; similarly, the azimuth of the north corner of the south  
building (E-III), as viewed from the same point on E-VII-sub, is  
107.5°, very close to the azimuth of nadir passage at a flat  
horizon.  The dates of solar zenith passage at Waxactun (latitude  
17.394°) are May 9 and August 3; the dates of nadir passage are  
February 1 and November 10.

Aveni and Hartung, in their seminal study of E-groups, identified the  
middle of the first platform of E-VII-sub as the position where the  
"best fit" to a functioning observatory is achieved (Aveni and  
Hartung 1989:444). In an important horizon study at Palenque, Mendez  
et al. have documented that sunrise on zenith passage at that site,  
as viewed from the doorway of the Temple of the Sun, occurs directly  
over the center of the roof comb of the Temple of the Cross  
(analogous to Str. E-1 at Waxactun)(Mendez et al. 2005:44)(This paper  
can be found at the Maya Exploration Center website,  
www.mayaexploration.org).

I was led to a closer examination of the Waxactun E-group by findings  
from the Chocola horizon study which established that, consistent  
with Aveni's conclusion in "Tropical Archaeoastronomy" (Aveni  
1981:161), zenith and nadir were the important reference poles for  
ancient tropical astronomers. At Chocola, as viewed from Mound 1 (the  
highest extant mound at the site), both zenith and nadir passages as  
well as the chronological midpoints between zenith passage and  
equinox and between equinox and nadir passage were marked by  
prominent natural features on the relatively distant horizon  
(mountain peaks or, in the case of zenith passage, the gap between  
two peaks, located from 16 to 56 km to the east), whereas there were  
no distinct horizon markers for the solstices or the equinoxes. If  
ancient Maya astronomers at Middle Preclassic Chocola (although the  
site has not yet been securely dated) marked solar zenith and nadir  
passages at the horizon, it would seem likely that E-groups  
constructed much later might have been used for these expanded  
observations as well.

The question has been raised as to how ancient tropical astronomers  
could have determined the day of solar nadir passage, since that  
event is not observable. A line from the point of a solar event  
(summer solstice sunrise, for example) at one horizon extended  
through the observer leads to the point of the counterpart event  
(winter solstice sunset) at the opposite horizon, assuming flat  
horizons. Thus, an ancient Maya astronomer standing atop a volcano  
(Atitlan, for example) at summer solstice sunrise could determine the  
point of winter solstice sunset by extending the line from the point  
of summer solstice sunrise through his position to the opposite  
horizon. Better, at summer solstice sunrise, the shadow of the  
volcano would serve as a pointer to the point of winter solstice  
sunset on the western horizon. This would work just as well for  
zenith passage sunrise and nadir passage sunset. I learned this from  
Karen Bassie who will deal with this at greater length in her  
forthcoming book on sacred landscape of the Maya.

Hal Green

On Feb 20, 2008, at 6:40 PM, Robert Hall wrote:

>      Please correct me if I am wrong, but I do not believe that the  
> literature on E-Groups considers the possible relevance of nadir  
> passage of the sun in addition to solstices and equinoxes. It has  
> been a puzzle that dates on stelae associated with the prototypical  
> Uaxactun E-Group do not relate to solstices or equinoxes. Using the  
> 584283 constant, the dates are February 1, 357 A.D., for the LC  
> date 8.16.0.0.0 on Uaxactun Stelae 18 and 19 and January 28, 495  
> A.D., for the date 9.3.0.0.0 on Stela 20. Each LC date marks a  
> katun-ending. Uaxactun has a latitude of about 17 degrees 24  
> minutes north latitude. At this latitude the sun makes its first  
> nadir passage on January 31. The dates on these Uaxactun stelae are  
> the only katun-ending dates that ever had or that ever would fall  
> close to a day of first nadir passage of the sun at the latitude of  
> Uaxactun during the occupation of this site. While solstices and  
> equinoxes are not affected by latitude, nadir and zenith passages of
>  the sun are. I have not and do not plan to investigate how this  
> might effect the variability of orientation of knock-off e-groups  
> at other sites, but it could be something to consider.
>        In another matter, I would like to be contacted by the  
> listero who expressed an interest in any Maya awareness of sundogs.  
> Sundogs actually have a rather important place in Aztec cosmology  
> and beyond, though not one related to structure orientations that I  
> am aware of.
>        Bob Hall
> _______________________________________________
> Aztlan mailing list
> http://www.famsi.org/mailman/listinfo/aztlan
> Click here to post a message Aztlan at lists.famsi.org
> Click to view Calendar of Events http://research.famsi.org/events/ 
> events.php
>
>