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Of particular interest among the some three hundred almanacs that make up the Maya codices are those that reveal the extraordinary sophistication of Maya astronomical practice. The Paris Codex, for example, contains a thirteen-constellation zodiac that implies that Maya astronomers tracked the movement of the sun, moon, and planets against the background of the stars (Figure 59.2). A Venus table in the Dresden Codex marks the first and last appearance of that planet in the morning and evening sky. An accompanying correction table allows the user to fit the canonic round of 584 days to the observed Venus cycle of 583.92 days to an accuracy of one day in five hundred years. That a similar table can be found in the central Mexican Codex Borgia may imply long-distance cross-cultural trafficking in ideas about the measure of time across ancient Mesoamerica (cf. Vail and Aveni 2004).

Other almanacs in the Maya codices incorporate mathematical mechanisms for reckoning the motion of Mars and eclipse warnings. Recent investigations posit that a number of almanacs previously thought to refer to endless cycles of 260 days may also have been intended to indicate adjustable seasonal points in a historical (“real-time”) framework (cf. Bricker and Bricker 2011, Vail and Aveni 2004). A similar example has also been proposed in the Borgia Codex (Milbrath 2007). While Mesoamerican astronomy is quantitative and precise, its end responds exclusively to astrological interests, namely securing predictions concerning crops, disease, rain, and so forth.

Though so much evidence relating to precontact calendrical practice has been destroyed, some information survives, though in modified form, in the post-conquest Books of Chilam Balam and Annals of the Cakchiquel in the Maya area. These several sacred historical books, housed in and named after towns that grew up around the Maya ruins, refer to particular ritual cycles, especially to prophecies that accompany katun endings. In addition, books by Spanish chroniclers (e.g., Durán and Sahagún in Mexico, and Landa in Yucatán) contain narratives that refer to calendrical divinatory procedures, calendar wheels, stars, names of constellations, planets, and eclipses. Though heavily corrupted by the Hispanic worldview, indigenous ideas and practices can nonetheless be extracted from these valuable data.

In addition to the excavation, restoration, and preservation of carved texts on the monuments, the archaeological record offers insight into the role of time, astronomy, and cosmology in urban planning, as well as in the architectural placement and orientation of particular structures. The interdisciplinary study of archaeoastronomy, lately renamed “cultural astronomy” (Ruggles and Saunders 1993), is the study of the practice of astronomy in ancient civilizations based on both written and unwritten records. A broad survey of the methodology and history of such studies is detailed in Aveni’s work (2001, 2003, 2008). Because sky events offer the most reliable seasonal and longer-term timing devices, one might expect celestial axes and pivots to play a role in architectural planning, especially where ceremonial activities are conducted, and most especially in cultures known to have exhibited an interest in sky phenomena based on the written and pictorial record. Herewith are a few examples.

According to the Aztecs, Teotihuacan was regarded as the place where time began when the sun was born. The deviation from cardinality as well from the lay of the land, by some 15½° clockwise, of the rigid rectangular grid structure of the city is likely owed, at least in part, to an attempt to duplicate the cosmos in the built environment. The east-west orientation of the city is directed toward the setting point of the Pleiades star group, which passed the overhead point when Teotihuacan was founded, ca. 200 BC. Moreover, the predawn appearance of the Pleiades in the east coincided with the date of the first two annual passages of the sun overhead. This clever sun-and-star timing device, incorporated into the spatial fabric of the city, may have served as a way of both controlling and celebrating time, a response to the cosmic mandate connecting rulership to transcendence. The 15½° axis also coincides with sunset positions forty days after the spring equinox and twenty days before first solar zenith passage, which may imply an attempt to configure the basic twenty-day Mesoamerican calendrical count into a horizon-based calendar, further linking city and cosmos. Sugiyama (2010) has proposed that multiples of basic calendrical periods such as 260-day and the 584-day Venus cycle served as measuring units applied to the dimensions and relative spacing of many of Teotihuacan’s basic structures. Local mountains and caves also appear to have played a role in the city plan. One can appreciate the problem confronting the architectural designers, who were faced with the practical problem of arranging their city to be in perfect harmony with the many manifestations of nature they believed lay at the source of their power.

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