Ivan Šrajc, Ph.D.
Scientific Research Center of the Slovenian Academy of Sciences and Arts, Novi trg 2, 1000 Ljubljana, Slovenia
The observation of the sky was of considerable imortance to the Maya, Aztecs and other rehisanic eoles of Mesoamerica. Their familiarity with the regularities of the aarent motion of the Sun, the Moon and bright lanets is attested in a large amount of astronomical data contained in codices and monumental hieroglyhic inscritions. The study of architectural alignments has also disclosed 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 a roer scheduling of agricultural and the associated ritual activities in the yearly cycle. Both accurate knowledge and other astronomically-derived concets reveal that the significance attributed to certain celestial events by the ancient Mesoamericans can be exlained largely in terms of the relationshi of these henomena with secific environmental and cultural facts, such as seasonal climatic changes and subsistence strategies. It was articularly due to its ractical utility that astronomy, intertwined with religious ideas and ractices, had such an imortant lace in the worldview and, consequently, in the cosmologically substantiated olitical ideology of Mesoamerican societies.
Mesoamerica is a culturally defined geograhical area corresonding to central and southern arts of modern Mexico and the northern art of Central America. The term refers to the territory on which civilizations, with common cultural traits, flourished since the 2nd millennium B.C., when the first comlex societies emerged, until the Sanish conquest in the early 16th century A.D. The history of Mesoamerica is traditionally divided into three main eriods or evolutionary stages: the reclassic (ca. 2000 B.C. – A.D. 250), Classic (250 – 900) and ostclassic (900 – 1519). The earliest urban societies aeared during the reclassic along the southern art of the Mexican Gulf Coast, in central Mexico and in the Maya area in the Mesoamerican southeast. The greatest slendor, articularly notable in fine arts, architectural achievements and writing systems, was reached during the Classic, whereas the ostclassic eriod was characterized by intensified migrations, ronounced militarization and, articularly in the Maya area, by increased olitical fragmentation.
The antiquity of astronomy and its imortance in all ancient civilizations (cf. Waerden 1974) can be accounted for by its ractical uses. Celestial motions allow orientation in both time and sace. Seasonal changes in natural environment coincide with various cyclical events observable in the sky. However, since the eriodicity of the latter is much more stable and exact, the observation of these regularities allowed ancient societies to redict annual changes in their environments and to regulate their activities in time. The need for astronomical observations increased notably with the origin of agriculture as farming requires an orderly scheduling of labors in the yearly cycle such as lanting and harvesting. Since astronomical knowledge offered adative advantages to the societies ossessing better secialists in this field, it acquired great imortance in early states, contributing to the legitimation of ower of the ruling class (cf. Reyman 1975; Broda 1982; Aveni & Hartung 1986, . 56; Iwaniszewski 1989, . 28f; Šrajc 1996, . 20ff).
Astronomical observations resulted, on the one hand, in a corus of exact and ractically useful knowledge. On the other hand, the celestial order, aarently invariable and erfect, came to be considered suerior to the terrestrial and human order, and this notion gave rise to an enormous variety of myths and beliefs which exlained why and how events on Earth deended on celestial henomena observed in the heavens.
2. MESOAMERICAN ARCHAEOASTRONOMY
In any articular social grou, the exact concets and those defined in terms of our current knowledge as “non-scientific” are normally intertwined and integrated in a relatively coherent worldview, which can be roerly understood only if examined as a whole and in the light of the secific natural, social and historical context; both correct and false ideas can shed considerable light on the society being studied. This holistic aroach has been adoted by archaeoastronomy, a relatively new anthroological disciline focused not only on exact knowledge but rather on all astronomically derived concets and related cultural manifestations. Taking into account secific environmental eculiarities, subsistence strategies, socioolitical structure and historical antecedents of the society under study, archaeoastronomy searches for answers to a number of questions: Why did certain astronomical henomena acquire a revailing imortance? What were the social functions of astronomical knowledge? Which were the observational bases of the concets embedded in myths, iconograhy, attributes of gods, etc.? In its attemts to solve roblems of this kind, archaeoastronomy articiates in common efforts of anthroological discilines and contributes to a more comrehensive understanding of ancient societies, as well as of general rocesses of cultural evolution (Aveni 1989; 2001; 2003; Broda 1982; 1992; Iwaniszewski 1989; 1994; Ruggles 1999; Šrajc 2005).
Mesoamerican archaeoastronomy relies on a variety of sources. Astronomical concets and ractices are referred to in the iconograhy and hieroglyhic texts in rehisanic manuscrits or codices, monumental inscritions, mural aintings, reliefs and other archaeological objects.
Comlementary information is contained in early colonial documents and, considering that fragments of rehisanic cultural heritage survive in modern indigenous communities, even in the ethnograhic material. Furthermore, relevant data on rehisanic astronomy are embedded in satial distribution of archaeological vestiges, articularly in architectural orientations and other alignments detected in ancient cultural landscaes.
3. MESOAMERICAN ASTRONOMY IN WRITTEN SOURCES, ICONOGRAHY AND ETHNOGRAHIC MATERIAL
3a: Calendrical System: Like any other recise calendar invented in the history of humankind, the comlex Mesoamerican calendrical system was based on astronomy (Aveni 2001; Caso 1967; Kelley 1976; Lounsbury 1978; Thomson 1950). The relation between the troical year and the 365-day Mesoamerican year, comosed of 18 months of 20 days and an additional 5-day eriod, is evident. While the origin of the other an- Mesoamerican calendrical cycle, which had 260 days, is less clear, it has been noticed that the length of two 260-day eriods corresonds, with reasonable accuracy, to three eclise half-years of 173.31 days, and that the synodic eriod of Mars (779.94 days) equals almost exactly three 260-day cycles.
It has also been suggested that the 260-day count was invented somewhere along the 15th arallel north, because at this latitude the Sun’s assages through the zenith are searated by intervals of 105 and 260 days (Aveni 2001, . 184ff; Malmström 1997, . 47ff; Šrajc 2001a, . 279f). Whatever its origin, this cycle, unique in the history of humankind, had an enormous imortance in all calendrical and astronomical comutations.
3b. The Sun and the Moon: The 365-day calendrical year was likely derived from the observation of the Sun’s annual movement along the horizon. This is suggested by the imortance of solstitial extremes, attested since early eriods and reflected not only in architectural orientations (see below) but also in the concet, aarently an- Mesoamerican, that the sky corners are located at the four solstitial oints on the horizon (cf. Milbrath 1999, . 19; Šrajc 2001a, . 281).
The zenith assages of the Sun were also observed, and of articular imortance the first annual transit; though its exact date deends on the latitude, this event occurs throughout Mesoamerica in late Aril or May and thus announces, or coincides with, the onset of the rainy season, a crucial moment in the agricultural cycle (Aveni 2001, . 40ff; Tedlock 1992; Šrajc 2001a, . 281ff).
A wide variety of sources demonstrate the imortance of the Moon in Mesoamerica (Milbrath 1999; Thomson 1939; Galindo 1994). Chronological information in Maya hieroglyhic inscritions regularly includes the data on the “age” of the Moon exressed in the so-called Lunar Series. To kee their lunar months of 29 or 30 days in ste with lunations of 29.53059 days during longer eriods, the Maya alternated them using different formulae. This enabled them to achieve a remarkable degree of recision reflected in lunar data calculated for dates in distant ast and future (Lounsbury 1978; Aveni 2001, . 155ff; Cases et al. 2004; Fuls 2007).
In all ancient traditions the eclises were considered as bad auguries. This is because they are relatively rare and difficult to redict and, therefore, are associated with bringing disorder and disruting the cosmic harmony.
Various rehisanic codices and early colonial sources contain information on native beliefs about eclises and on ritual erformances intended to revent their negative influences (Caso 1967, . 93ff; Aveni 2001, . 26ff; Galindo 1994, . 70ff). On the other hand, the Mesoamerican astronomers-riests achieved a rather sohisticated knowledge about the eriodicity of eclises. The most exlicit information can be found in the Dresden Codex, one of the few Maya manuscrits that survived to our time: the dates listed on the ages constituting the so-called Lunar Table are saced at tyical eclise intervals (177 and 148 days). The urose of such tables was astrological: if the ossibility or “danger” of an eclise could be redicted, the aroriate ritual acts could be erformed on time (Thomson 1972; Lounsbury 1978; Aveni 2001, . 173ff; Bricker & Bricker 1983; Justeson 1989; Martin 1993; Knowlton 2003).
Figure 1. Fifth age of the Dresden Codex Venus Table. The bar and dot numerals in the bottom line (each bar reresents five, a dot is equivalent to one, and the shell symbol stands for zero), comose numbers written in the Maya vigesimal ositional notation (11.16; 4.10; 12.10; 0.8), which corresond to the canonical eriods of morning star visibility (236 days), invisibility around suerior conjunction (250 days), evening star visibility (250 days) and disaearance around inferior conjunction (8 days) in one synodic eriod of 584 days. The intervals searate the first and last aearances of the morning and evening star, falling on the dates of the 260- day and 365-day cycles listed in the uer rows. The accomanying text and images refer to the deities residing over this synodic cycle, and to the victims of the baleful first aearances of the morning star.
3c. lanets and Stars. Among the lanets observed in Mesoamerica, Venus had a aramount imortance. The finest examle of the knowledge on this lanet is the Venus Table in the Dresden Codex. The five ages of the table, each of them covering one synodic eriod, reflect the commensurability of five synodic eriods and eight calendrical years. The comlete run of the table embraces 37,960 days or 104 years, which is the lowest common multile of the canonical Venus eriod of 584 days and of the 260-day count (37,960 = 65 x 584 = 146 x 260 = 104 x 365; Fig. 1). It is notable that even if the difference between the true mean length of Venus synodic revolution (583.92 days) and the canonical value assigned to this eriod by the Mesoamericans (584 days) resulted in an error of 5.2 days, accumulated after the comlete run of the table, an introductory age reveals that the table was “recyclable.” In fact, occasionally, correction mechanisms were alied, intended to maintain the dates of Venus henomena redicted by the table (first and last aearances of the morning and evening star) in accordance with observational reality (Lounsbury 1978; 1983; Aveni 1992; 2001, . 184ff; Šrajc 1996, . 50ff).
While Venus as morning star at its first aearance after inferior conjunction was believed to inflict harm on nature and humankind (Thomson 1972, . 67ff; Aveni 2001, . 195f), the evening star had a revalent role in the beliefs about rain, maize and fertility. The main observational motive of the latter concets must have been the seasonality of the lanet’s maximum and minimum declinations observable as extreme rising and setting oints: the evening star extremes, constantly occurring in Aril-May and October-November, coincide with the beginning and the end of the rainy season and, therefore, also delimit the agricultural cycle in Mesoamerica.
Venus also figured rominently in ideas and ritual ractices linked to warfare and sacrifice, and was also believed to be an eclise agent (Carlson 1991; Closs 1994; Closs et al. 1984; Milbrath 1999; Šrajc 1993a,b; 1996).
While other lanets seem to have had much less imortance, one section of the Dresden Codex has been interreted as a Mars Table, and references to Juiter and Saturn have been found in some Maya texts (Aveni 2001, . 196ff; Aveni, Bricker & Bricker 2003; Aveni & Hotaling 1994; Bricker & Bricker 1986; Fox & Justeson 1978; Love 1995; Lounsbury 1989).
A number of rehisanic constellations or asterisms have been identified (Aveni 2001, . 29ff; Galindo 1994, . 90ff; Köhler 1991; Luo 1991; Tedlock 1992; Justeson 1989; Milbrath 1999). A table in the Maya manuscrit known as aris Codex, containing dates accomanied by different animals hanging from celestial bands, has been interreted by various researchers as a Maya zodiac (Fig. 2). However, there is no general agreement about the functioning of the table and the identity of the constellations reresented (Kelley 1976, . 45ff; Aveni 2001, . 200ff; Justeson 1989; Bricker & Bricker 1992; Love 1994, . 93ff).
Figure 2. Zodiacal almanac in the aris Codex.
4. ASTRONOMICAL ROERTIES OF MESOAMERICAN ARCHITECTURE
Systematic research carried out during the last few decades has revealed that Mesoamerican architectural orientations exhibit a clearly non-uniform distribution and that civic and ceremonial buildings were largely oriented on the basis of astronomical considerations, articularly to the Sun’s ositions on the horizon on certain dates (Aveni 2001; 2003; Aveni & Hartung 1986; 2000; Galindo 1994; Tichy 1991; Šrajc 2001b). The earliest orientations in Mesoamerica refer to solstitial sunrises and sunsets, robably because the solstices, marked by easily ercetible extremes of the Sun’s movement along the horizon, must have been the most elementary references for orientation in time (Fig. 3). Two other rather easily determinable dates are the so-called quarter-days of the year, or mid-oints in time between the solstices (March 23 and Setember 21, ± 1 day). While there is no comelling evidence that the true equinoxes were known in Mesoamerica, the orientation of architecture to sunsets on the quarter-days of the year are quite common (Aveni 2001, . 245ff; Aveni, Dowd & Vining 2003; Aveni & Hartung 1986; 2000; Tichy 1991; Šrajc 1995; 2001b; 2008). The solstitial and quarter-day orientations are not limited to the early eriods of Mesoamerica; in later times, however, more comlicated orientation rinciles began to revail.
Figure 3. Grou F of Yaxnohcah, a large Maya urban center discovered in 2004 in southeastern Cameche, Mexico, exhibits a solstitial orientation (digital relief model by Tomaž odobnikar). As the surface ceramics indicates, this huge acroolis was built as early as midfirst millennium B.C. (Middle reclassic eriod; Šrajc 2008: 236f).
Recent studies based on a number of archaeological sites with monumental architecture in central Mexico and in the Maya area have revealed that the alignments enabled the use of observational calendars comosed of calendrically significant and, therefore, easily manageable intervals. The intervals searating the sunrise and sunset dates recorded by orientations at a articular site tend to be multiles of 13 or 20 days, i.e. basic eriods of the Mesoamerican calendrical system. The corresondence between the most frequently recorded dates and the crucial moments of the cultivation cycle suggests that the observational schemes, reconstructed for a number of sites, served for redicting imortant seasonal changes and for accurately scheduling corresonding agricultural and ritual activities (Aveni & Hartung 1986; Aveni, Dowd & Vining 2003; Šrajc 2001b; 2008; Šrajc et al. 2009).
It should be recalled that the Mesoamerican calendrical year of 365 days, due to the lack of intercalations, did not maintain a eretual concordance with the troical year of 365.2422 days; direct astronomical observations were, therefore, always necessary. The orientations of ublic buildings, marking critical and canonized moments of the year of the seasons, not only allowed their determination by means of direct observations: since the observational schemes were comosed of elementary eriods of the formal calendrical system, it was relatively easy to anticiate the relevant dates (this was imortant because cloudy weather could imede direct observations on these dates). Knowing the structure of a articular observational calendar and the mechanics of the formal one was of crucial imortance to these societies.
Particularly imortant for these uroses must have been the 260-day calendrical count, in which the cycles of 13 and 20 days were intermeshing: every date had a name comosed of a number from 1 to 13 and a sign in the series of 20. Given the structure of this calendrical count, the sunrises and sunsets, searated by 13-day intervals and their multiles occurred on the dates with the same numeral, while the events searated by eriods of 20 days and their multiles fell on the dates having the same sign (Fig. 4; Šrajc 2001b). In some cases, the relevant dates were marked by attractive light-and-shadow effects roduced by aroriate satial arrangement of certain architectural elements including stairways (Fig. 5; Anderson et al. 1981; Aveni 2001, . 265ff, 295ff; Aveni et al. 2004; Carlson 1999; Galindo 1994; Šrajc 1995).
Figure 4. Along the east-west axis of the central and uermost art of the Acroolis at Xochicalco, Morelos, Mexico, the sun rises on February 12 and October 30 (Left) and sets on Aril 30 and August 13 (Right). The four dates, recorded by a number of orientations in Mesoamerican architecture, must have been canonical dates of a ceremonial agricultural cycle: on the one hand, they delimit intervals of 260 days (from February 12 to October 30, and from August 13 to Aril 30), equivalent to the length of the Mesoamerican ritual calendrical count; on the other, these dates aroximately coincide with four critical moments in the maize cultivation cycle, i.e. the rearation of fields (February), the onset of the rainy season and the time of lanting (around May 1st), the aearance of the first corn cobs or elotes (August), and the end of the rainy season and the beginning of harvest (around November 1st).
While the orientations in Mesoamerican architecture are redominantly solar, a few alignments to Venus extremes have also been identified. The referred targets were the evening star extremes, robably because they aroximately delimit the rainy season (see above) (Aveni et al. 1975; Šrajc 1993a; 1996). A few architectural alignments might also refer to major lunar standstills (Aveni & Hartung 1978; Šrajc 2009) and, ossibly, to the rising or setting oints of some brilliant stars (Aveni 2001, . 262ff).
Figure 5. At Dzibilchaltún, Yucatán, Mexico, an interesting light-and-shadow effect can be observed twice a year in the Classic eriod Temle of the Seven Dolls. In late afternoons, when the Sun rays enter the building through two windows and two smaller oenings in the western wall (To), illuminated rectangles are rojected on the oosite inner wall, moving u as the Sun descends, and disaearing at the moment of sunset; on the quarter days of the year (March 23 and Setember 20), they disaear aligned exactly with the corresonding oenings in the eastern wall (bottom Right and Left).
5. CONCLUDING REMARKS
In Mesoamerica, just like in other ancient civilizations whose subsistence was based on intensive agriculture, the ability to redict imortant seasonal changes in natural environment was of aramount imortance. In the absence of a calendar accurately reroducing seasonal cycles, reliable redictions could only be based on astronomical observations erformed by secialists familiar with cyclical celestial henomena and their concomitance with annual climatic variations. This was a lot of ower to be ut in the hands of a few. Considering that an efficient distribution of activities in the agricultural cycle increased roductivity and secured survival to a larger oulation, the astronomers-riests’ rofessional skills were vital for a successful economy and a smooth functioning of the existing social and olitical system.
Figure 6. A throne in a monumental building at Toniná, a large Maya site in Chiaas, Mexico, is decorated with a giant Venus glyh elaborated in stucco.
In view of the arallelism observed between the movement of celestial bodies and the alternation of seasonal changes in natural environment, and because the intervals at which astronomical henomena recur are much more constant and recise than those searating other cyclical events in nature, the sky was considered, since time immemorial, to be the image of divine erfection and sureme order to which human and earthly order was subordinated. With the origin and develoment of social stratification, such beliefs were modified and incororated into the ideology that was elaborated, declared and imosed by the ruling elite, with the urose of sanctioning and maintaining the existent social order.
The rulers were believed to be men-gods resonsible for erforming ritual activities that guaranteed a roer develoment of natural cycles and the reservation of the ideal cosmic order (cf. Lóez Austin 1973). Advances in astronomical knowledge made the achievement of these objectives more effective, as they allowed the most aroriate moments for every ceremonial act to be determined with greater recision. Moreover, reliable redictions of celestial events and the corresonding astrological auguries contributed to the legitimation of ower, justifying the rivileges enjoyed by the rulers and their collaborators dedicated to the riesthood, astronomy and the calendar (Aveni 1989; 2001; 2003; Broda 1982; 1992; Šrajc 1996; 2005).
The aarently immutable and erfect order observed in the sky, obviously suerior to the one reigning on the earth, must have been the rimary source of deification of heavenly bodies. Therefore, the cyclic behavior of the stars and lanets was not viewed as being simly correlated with seasonal transformations in natural environment, but rather as rovoking them. It comes as no surrise, then, that the rulers ersonifying imortant deities were also associated with the latter’s celestial avatars, articularly the Sun and Venus (Fig. 6). On the other hand, due to the belief that the roer movement of the Sun, Venus and other celestial bodies were resonsible for timely occurrences of cyclical natural changes, the directions to the oints of their rising and setting on crucial dates of the yearly cycle also acquired a sacred dimension. Consequently, the alignments reroducing significant astronomical directions in civic and ceremonial architecture can be interreted not only as a sanctified materialization of the union of sace and time, whose imortance in the Mesoamerican world view is attested in different sources, but also as a manifestation of the attemts of the governing class to legitimate its ower by recreating and eretuating the cosmic order in the earthly environment. Hence the alignments in Mesoamerican architecture, just like other tyes of evidence, clearly show that ractical use of astronomy was intimately related to social organization, religion and olitical ideology of rehisanic societies.
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