It is known that the grid pattern characterizing the city layout of Teotihuacan incorporates two slightly different groups of alignments, skewed approximately 15.5% and 16.5% clockwise from cardinal directions. I argue that these alignments were dictated by deliberate and astronomically functional orientations of the Pyramid of the Sun and the Ciudadela. The two structures recorded sunrises and sunsets on two different sets of dates, allowing the use of an observational calendar composed of intervals that included multiples of 20 days and a 260-day period. The evidence presented suggests also that the location of the Sun Pyramid was not determined by the cave that is now underneath the structure and is probably human-made, but rather by a combination of astronomical and topographic criteria: the place allowed the temple built there to be oriented both to sunrises and sunsets on significant dates and, in the perpendicular direction, to Cerro Gordo to the north; furthermore, sunrises on the so-called quarter-days of the year could be observed from the same spot over a prominent mountain on the eastern horizon. The dates corresponding to the Teotihuacan alignments are attested also at other central Mexican archaeological sites and must have been employed, primarily, for scheduling agricultural and associated ritual activities in the yearly cycle.
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... The selection of structures to be measured was based on the assumption that the orientational rules reflecting astronomical concepts and related aspects of worldview and religion were more strictly adhered to in civic and ceremonial architecture. If two or more buildings composing an architectural group were found to share a particular orientation, only that of the most prominent structure was considered in the analyses, assuming that those of the adjacent buildings roughly reproduced it but were not observationally functional per se (the most eloquent example is the urban grid of Teotihuacan;Š prajc 2000b. ...
This article synthesizes recent advances in the study of astronomy and worldview in architectural and urban planning in Mesoamerica. Throughout most of this cultural area, the practice of orienting civic and ceremonial buildings followed similar principles, although regional and time-dependent variations are present. Analysis of alignment data has revealed the existence of distinct and widespread orientation groups; most refer to sunrises and sunsets on particular dates, although two groups can be related to lunar and Venus extremes. Astronomically relevant directions frequently dominate considerable parts of urban layouts. The orientation and the location of important buildings often were conditioned by astronomical criteria and beliefs about specific landscape features; particularly notable are structures that were aligned to prominent mountaintops on the local horizon. Based on a variety of contextual data, I interpret the uses and significance of orientations in terms of agricultural concerns, cosmological concepts, and political ideology. I outline the evolution of orientation practices, drawing attention to pan-Mesoamerican trends, regional patterns, and diffusion processes.
... Examining building orientations at Teotihuacan, Ivan Sprajc postulated that these alignments and their relation to the annual path of the sun could have been employed to observe calendric cycles, including the definition of an interval that lasted 260 days (Sprajc 2000). He noted that it was at Teotihuacan that two slightly different orientations first appeared together, which made possible an observational calendar (Sprajc 2015(Sprajc , 2018. ...
Archaeoastronomical studies carried out during the last decades in Mesoamerica have demonstrated that civic and ceremonial buildings were largely oriented on astronomical grounds, mostly to sunrises and sunsets on certain dates, allowing the use of observational calendars that facilitated the scheduling of agricultural and related ritual activities. One of the deeply rooted but unfounded ideas is that many alignments recorded the Sun's positions at the equinoxes. By examining such proposals and analyzing their methodological flaws, I argue that they are not based on reliable and objectively selected alignment data, but rather derive from the preconceived significance attributed to the equinoxes. The most likely targets of the near-equinoctial orientations were the so-called quarter days, which occur two days after/before the spring/fall equinox and mark mid-points in time between the solstices. Considering that the astronomical alignments dominate extensive parts of the built environment, they must have played an important role in religion, worldview, and political ideology. Therefore, only a correct identification of their celestial referents, a prerequisite for any convincing interpretation of their meaning, underlying intents, and observational practices employed, can contribute to a proper understanding of some prominent aspects of architectural and urban planning in Mesoamerica.
Unlike most cities of the ancient Maya, the ancient city of Teotihuacan was never completely overgrown by tropical forests, never deeply buried in layers of sediment, nor entirely lost to the residents of northern Mexico. Located 50 kilometers (30 miles) northeast of Mexico City, the city ruins remain one of the most important monuments of Mexico.
In this paper, we discuss the astronomical orientations in the city plans of Teotihuacan and Tenochtitlan. Mesoamerica exhibits much archaeoastronomy and these two sites are rich examples. Both exhibit alignments for solar horizon events that are integral in deliberate calendrical systems. The logic of these systems is shown, and this demonstrates that these cities were carefully planned with astronomical knowledge.
The site of Nahualac (3890–3920 m asl) is situated on the western slopes of Iztaccihuatl, a well-known volcano in Central Mexico. It consists of a rectangular stone sanctuary located within the seasonally active small lagoon, and the distinct area where multiple deposits of ritual pottery were found. The piles of stone situated on the borders of the lagoon produce alignments towards the nearby and distant landforms offering broad vistas towards the brilliant white peaks of Iztaccihuatl in the East and restricting the visibility towards the West. The site belongs to the category of high-mountain cult places functioning during the Early and Late Post-classic periods (900–1521 CE) and is associated with the central Mexican cult of fertility, mountain, and rain. The ritual and worldview meanings of this site are taken together to discuss the ways of how the Post-classic societies in Central Mexico conceptualised their relationship with their surroundings. Using the layout of Nahualac and its astronomical alignments, I conclude that it exhibited cultural configurations that can be classified as characterising analogism rather than animism.
The connection between astronomy and daily life in ancient times—at least after the definitive establishment of sedentarian life—was far more complex than a simple understanding of natural cycles. We can be sure of this because the sky was linked to a fundamental mechanism of social dynamics: the management of power. To grasp the connection between astronomy and power, however, first we must make a detour to understand the concept of worldview.
Research presented here demonstrates that an unusual almanac in the Madrid Codex (pages 12–18) integrates observations of the Venus cycle with eclipse events in the context of the agricultural year. Imagery in the 260-day almanac represents eclipse glyphs associated with Tzolkin dates that coordinate with eclipses visible in Yucatan during the fifteenth century, indicating the almanac dates to the Late Postclassic. The almanac also depicts seasonal events in the context of a repeating pattern of paired solar eclipses associated with observations of Venus as the evening star. Quetzalcoatl-Kukulcan's counterpart in the Madrid almanac is the Chicchan serpent, who plays the role of Venus in a sequence showing a fertile aspect of the planet linked with the 260-day agricultural cycle and the Pleiades. Clearly, Venus positions and eclipse events were closely watched in relation to the planting cycle, reflecting a form of “agro-astronomy” that we are only now beginning to understand.
Members of the Proyecto Arqueológico de la Biosfera Calakmul under Carrasco's direction excavated the Cenote Style Group E-type complex at the Maya site of Calakmul, Campeche, Mexico. The Cenote Style refers to the plan of the E-Group with a series of three temples built onto a long narrow eastern range structure facing a western structure across a broad central plaza. Architectural data exist to evaluate this standardizing group's utility for observing solar events. Astronomical evidence for the function of this complex is presented and discussed. The overall orientation of Structures IVa, IVb, IVc, and VI is slightly east, 13° of true north, while a pair of doorways in Structure IVc align with the setting sun during the summer solstice point, despite the break in the buildings' floor-plan symmetry this represents.
Intervals of 260 days are recorded by architectural orientations at a number of Maya sites, a pattern that may have developed early at sites such as Nakbe. The 260-day calendar, emphasizing sets of 13 and 20 days, dates back to the Middle Preclassic, when early E-Groups in the Maya area were used for solar observations. These observations were probably linked with a maize cycle spanning 260 days. By the end of the Late Preclassic, however, most E-Groups were abandoned or modified for a different function, serving as a stage for rituals performed by rulers at a time when the Long Count calendar was being developed. The changing role of E-Groups relates to the rise of royal rituals associated with the detailed historical records documented in Maya Long Count inscriptions.
Teotihuacán was probably laid out from its inception according to a master plan intended to express a specific worldview in material form. It is argued that a proposed measurement unit of 83 cm reveals mesoamerican calendrical numbers such as 52 (x 10), 73, 260, 584, and 819, when applied to city axes and major monuments. The channelized Río San Juan divides the central zone into two sections: the watery underworld to the south, especially represented at the Ciudadela, and to the north the earthly representation of the passage from the underworld to the heavens, where the Sun Pyramid at the center symbolizes a sacred time bundle in the 260-day ritual calendar. The sacrificial burial complex found at the Feathered Serpent Pyramid seems to have been a part of the city-foundation program, and the iconography of the pyramid apparently commemorated this dramatization of the creation of time and space.
[English] This paper reevaluates the architectural remains atop Mount Tlaloc in light of recent contributions by Aveni et al. (1988), Broda (1989, 1991a, 1991b), and Townsend (1991). Evidence suggests that there were at least two phases of architectural activity on the mountain. An archaeoastronomical analysis of the ceremonial enclosure leads to the suggestion that the orientation of the structure reveals a paradigm marking out specific days by denoting positions of the sun-at-horizon events at intervals of 20 days. This may be a reference to the nemontemi days of the Mexican 365-day solar calendar. Mount Tlaloc also appears to be associated with other mountains through visual lines that correlate with sunrise on dates when ceremonies were performed in sanctuaries situated on prominent elevations. // [Spanish] A la luz de las contribuciones recientes de Aveni et al (1988), Broda (1989, 1991a, 1991b), y Townsend (1991) se re-evalúan los restos arquitectónicos en la cumbre del Cerro Tláloc. La evidencia sugiere que hubieron por lo menos dos fases de construcción en la montaña. La investigación arqueoastronómica del recinto ceremonial hace suponer que la orientación de la estructura revela un paradigma mostrando los días determinados a través de la denotación de las posiciones del sol en el horizonte en los intervalos de 20 días. Posiblemente hay una referencia a los días nemontemi del calendario mexicano de 365 días. Cerro Tláloc parece también asociarse a otras montañas por medio de las líneas visuales que corresponden a las salidas/puestas del sol en días del calendario cuando se llevaban a cabo las ceremonias en los santuarios colocados en alturas relevantes.
A tendency for many precolumbian buildings to align east of north is examined for possible astronomical motives. Stellar and solar phenomena are suggested as possible influences. The importance of clearly establishing the relative positions of observer and point of reference in any archaeo-astronomical analysis is emphasized. Certain misconceptions concerning chronological correlations of alignments and a new dimension in establishing orientations are discussed.
The streets of this Classic period city were laid out in a grid pattern. The axes of this grid were almost, but not exactly, perpendicular. There were a number of celestial bodies that in the period from A.D. 150 to A.D. 750 rose or set so as to markthe orientations of the streets. The Pleiades, Sirius, and the sun were the most probable orientation points. Two techniques which have been developed to test the more certain past existence of celestial references are described.
The cave recently discovered underneath the Pyramid of the Sun in Teotihuacan, Mexico, is analyzed both according to historical written sources and reports of cults to cave deities, prominent in Mexico for millennia. Different cave rites are discussed in an effort to determine the function of the grotto. The Teotihuacan cave is compared with the mythical Chicomoztoc, Seven Caves, place of creation in ancient Mexican mythology. The author suggests that the cavern may have determined the site for the building of the Pyramid of the Sun and that later Aztec accounts of rulers being buried underneath the pyramid may have been based upon fact.
In the light of the recent excavations of the Templo Mayor in downtown Mexico City, we explore the problem of the role of astronomy, calendar, and the landscape in the design and orientation of the building and of the city in general. We employ ethnohistoric data relating to the foundation myth of Tenochtitlan as a means of generating hypotheses concerning astronomical orientation that can be tested by reference to the archaeological record. We find that eastward-looking observations (implied in dismantling and reconstructing the myth) that took place around the time of the equinox may have been related to an attempt to transform a true east orientation from the natural environment into the architecture via a line that passed through the center of the Temple of Huitzilopochtli (the more southerly temple of the pair constituting the top of the Templo Mayor). It also is possible that the notch between the twin temples served a calendrical/orientational function. Evidence is presented to support the view that the mountain cult of Tlaloc, represented in the environment on the periphery of the Valley of Mexico by Mount Tlaloc, also may have directly influenced the orientation of the building and that it was part of a scheme for marking out days of the calendar by reference to the position of the rising sun at intervals of 20 days from the spring equinox. In this regard, we discuss the connection between the Templo Mayor and an enclosure containing offertory chambers atop Mount Tlaloc, which is located on a line extended to the visible horizon 44 km east of the ceremonial center. The ethnohistoric record implies that this place had been used for sacrifices to the rain god after whom the other of the twin temples of the Templo Mayor was named.