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All Mesoamerican cultures had a calendar, that is, a way of organizing time. The Mesoamerican calendar had a common identity, just like the civilization that generated it, with an origin that dates back to about a thousand years before the Christian era, and multiple versions. Among the most representative are the Mayan calendar of the classic period and the Nahua-Mexica calendar of the postclassic period.
The Mesoamerican calendar was structured around the combination of two calendar rounds: one lasting 365 days called xiuhpohualli in Nahuatl or haab in Maya, ” count of the year “, and a second round lasting 260 days called tonalpohualli in Nahuatl or tzolkin in maya, ” count of the days “. The first cycle corresponds to the solar year, but its origin is unknown for the second, although it is estimated that it is associated with the cycles of the Sun, the Moon and the planet Venus.
Records of the calendar and its dates are chiseled on stone stelae, painted on tomb walls, engraved on stone sarcophagi, and written in codices. The Mayan codices are records written on a type of paper that they obtained using bark, written with glyphs, symbols that represented words. There are four codices that are preserved, and they are named according to the city in which they are exhibited. The Mesoamerican calendar was deciphered in the Dresden codex, perhaps the most important of the four. The 39 pages of the Dresden codex describe the use of the calendar, as well as predictions of solar and lunar eclipses, and the cycle of the planet Venus, as well as other astronomical knowledge.
The oldest form of the calendar, the 365-day haab cycle , was probably invented by the Olmecs, between 900 and 700 BC, when agriculture developed. The oldest confirmed combination of the haab cycle and the 260-day tonalpohualli cycle was identified in the valley of Oaxaca at the site of the Zapotec capital of Monte Albán. There, Stela 12 has a date that refers to the year 594 BC.
The calendar
The xiuhpohualli or haab cycle was made up of 18 periods of 20 days each, to which five additional days were added to complete the 365 days. The 18 periods of 20 days formed the Nahua series atlcahualo-izcalli , pop-cumkú in Maya, and the five complementary days were called nemontemi in Nahuatl and uayeb in Maya.
The tonalpohualli or tzolkin cycle was made up of 20 periods of 13 days each, thus totaling 260 days. Each day of this cycle had its own name, made up of two elements that were combined: a number from 1 to 13, and a sign from the cipactli-xóchitl series among the Nahuas, or imix-aháu among the Mayas. The following figure shows how the tonalpohualli or tzolkin cycle was structured, and how the name of each day is assigned. In the figure you can see the Mayan numeral form, which was vigesimal: it consisted of twenty symbols that were later repeated (our decimal number system has 10 symbols, from 0 to 9). A dot marked one unit and a dash equaled 5 units, while zero was represented by a shell.
The two cycles, the two calendar wheels, rotated simultaneously, combined to identify the days, and required the passage of 18,980 days for the combinations of the tonalpohualli wheel to rotate within the xiuhpohualli to be exhausted , and the identification had to be repeated there. of a day This is a cycle of 52 years that among the Nahuas was called xiuhnelpilli , a group of years that included 73 tonalpohualli .
Each of the 52 years had its own name, made up of a number from 1 to 13 and one of four day signs; Said name corresponded to that of a day of the tonalpohualli in a certain position within the xiuhpohualli . Among the Nahuas of the Post-Classic period the year-bearing signs were tochtli , ácatl , técpatl , and calli , while among the Maya of the Classic period these signs were manik , eb , cabán , and ik . The cyclical combination between the xiuhpohualli and the tonalpohualli will be called the calendar round.
The Nahuas and the Mayas used abbreviations for the dates, which in full form had to include the day of the tonalpohualli, the ordinal within twenty, and the year. The Nahuas indicated only the day of the tonalpohualli and the year; for example 8 ehécatl of 1 ácatl . The Mayans indicated the day and the ordinal within the twenty; for example 4 aháu 8 cumkú .
One of the best-known works of Aztec art is the Sun Stone. Glyphs representing the twenty days of the tonalpohualli cycle can be seen on the outer ring. Each of these days had a particular significance and, as in most forms of astrology, an individual’s destiny could be determined based on their date of birth. Wars, marriages, planting crops, everything was planned based on the most propitious days. A relevant astronomical event is related to the constellation Orion, since around the year 500 BC it disappeared from the sky between April 23 and June 12, its disappearance coinciding with the first planting of corn, and its reappearance when the corn sprouted.
leap year
The rotation period of the earth is 365.5 hours and 48 minutes, so the 365-day calendar must be adjusted by adding one day every four years, the leap year in the Julian calendar (the Gregorian calendar includes a further adjustment). accurate). Both the Maya and the Nahuas determined the length of the year accurately, so it is likely that they adjusted for the difference. In reference to the post-classic Maya period, Fray Diego de Landa recorded: « They had their perfect year like ours, of 365 days and 6 hours. Of these 6 hours, a day was made every four years, and thus, four in four years, they had a year of 366 days ». And regarding the Nahua-Mexicas, Fray Bernardino de Sahagún wrote: «In what [the anonymous priest] says that they were missing in the leap year, it is false; because in the account that is called the true calendar they count 365 days, and every four years they count 366 days ».
The historical records provide the information that the Spaniards who accompanied Hernán Cortés entered the city of Mexico-Tenochtitlan on Tuesday, November 8, 1519, corresponding to the Nahua date: day 8 ehécatl, ninth day of the twenty quecholli , of the year 1 ácatl . From this cross reference and knowing the general structure of both calendars, the Mexica calendar can be reconstructed and correlated with the Julian calendar. But this correlation is only valid if it is verified that the Mesoamerican calendar made the leap year adjustment.
Archaeologists believe that the calendar was constructed from astronomical data obtained by observing the movements of the evening star Venus (actually a planet) and solar eclipses. Evidence of this is found in the Madrid codex (Troano codex), a codex of the Maya of Yucatan that probably corresponds to the second half of the fifteenth century after Christ. On pages 12b-18b you can find a series of astronomical events in the context of the Tzolkin cycle., recording solar eclipses, the cycle of Venus and solstices. Astronomical observatories were identified in several places in Mesoamerica. In the Mayan city of Chichen Itza, in the Yucatan peninsula, one of them was found, the photograph of which is shown on the cover of this article. The Caracol, named for having a spiral staircase inside, is also called the Observatory. Its circular plan on two rectangular platforms with different orientations is an exceptional feature in Mayan architecture, and suggests its use as an astronomical observatory. Another astronomical observatory was identified in Building J of the Monte Albán archaeological site.
The Maya long count is another calendrical, non-cyclical form that began to be used from the Late Preclassic period. The number 20 is present in the long count , just like in the number system. The long count is based on a period of 20 days, Vinal or Uinal which, grouped in 18, forms the Tun cycle. And 20 tues form the Katun cycle, equivalent to 19.7 years; 20 katuns make up the Baktun cycle, 394.25 years, and the Baktun is the thirteenth part of the long count . Correlating it with the current calendar, the long count begins its record, on calendar day zero, August 11, 3113 BC.
Sources
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