The Aztec sun stone, often erroneously called the calendar stone, is on display at the National Museum of Anthropology in Mexico City.
The actual Aztec calendar consists of a 365-day calendar cycle called xiuhpōhualli (year count), and a 260-day ritual cycle called tōnalpōhualli (day count). These two cycles together form a 52-year "century", sometimes called the "calendar round". The xiuhpōhualli is considered to be the agricultural calendar, since it is based on the sun, and the tōnalpōhualli is considered to be the sacred calendar.
Tōnalpōhualli
The tōnalpōhualli ("day count") consists of a cycle of 260 days, each day signified by a combination of a number from 1 to 13, and one of the twenty day signs. With each new day, both the number and day sign would be incremented: 1. Crocodile is followed by 2. Wind, 3. House, 4. Lizard, and so forth up to 13. Reed. After Reed, the cycle of numbers would restart (though the twenty day signs had not yet been exhausted), resulting in 1. Jaguar, 2. Eagle, and so on, as the days immediately following 13. Reed. This cycle of number and day signs would continue similarly until the 20th week, which would start on 1. Rabbit, and end on 13. Flower. It would take a full 260 days (13×20) for the two cycles (of twenty day signs, and thirteen numbers) to realign and repeat the sequence back to 1. Crocodile.
Day signs
The set of day signs used in central Mexico is identical to that used by Mixtecs, and to a lesser degree similar to those of other Mesoamerican calendars. Each of the day signs bear an association with one of the four cardinal directions.[1][2]
There is some variation in the way the day signs were drawn or carved. Those here were taken from the Codex Magliabechiano.
Wind and Rain are represented by images of their associated gods, Ehēcatl and Tlāloc respectively.
Other marks on the stone showed the current world, and the worlds before this one. Each world was called a sun, and each sun had its own species of inhabitants. The Aztecs believed that they were in the Fifth Sun, and like all of the suns before them, they would also eventually perish due to their own imperfections. Every 52 years was marked out due to the belief that 52 years was a life cycle and at the end of any given life cycle, the gods could take all they had, and destroy the world.
Trecenas
The 260 days of the sacred calendar were grouped into twenty periods of 13 days each. Scholars usually refer to these thirteen-day "weeks" as trecenas, using a Spanish term derived from trece "thirteen" (just as the Spanish term docena "dozen" is derived from doce "twelve"). The original Nahuatl term was "in cencalli tonalli" (a family of days), according to Book IV of the Florentine Codex.
Each trecena is named according to the calendar date of the first day of the 13 days in that trecena. In addition, each of the twenty trecenas in the 260-day cycle had its own tutelary deity:
In ancient times the year was composed of eighteen months, and thus it was observed by the native people. Since their months were made of no more than twenty days, these were all the days contained in a month, because they were not guided by the moon but by the days; therefore, the year had eighteen months. The days of the year were counted twenty by twenty.
Xiuhpōhualli is the Aztec year (xihuitl) count (pōhualli). One year consists of 360 named days and 5 nameless (nēmontēmi). These 'extra' days are thought to be unlucky. The year was broken into 18 periods of twenty days each, sometimes compared to the Julian month. The Nahuatl word for moon is metztli but whatever name was used for these periods is unknown. Through Spanish usage, the 20-day period of the Aztec calendar has become commonly known as a veintena.
Each 20-day period started on Cipactli (Crocodile) for which a festival was held. The eighteen veintena are listed below. The dates are from early eyewitnesses; each wrote what they saw. Bernardino de Sahagún's date precedes the observations of Diego Durán by several decades and is before recent to the surrender. Both are shown to emphasize the fact that the beginning of the Native new year became non-uniform as a result of an absence of the unifying force of Tenochtitlan after the Mexica defeat.
nēmontēmi (“they fill up in vain”); Not a veintena, 5-day complementary period
Feb 24–Feb 28
Jan 28–Feb 01
None
Xiuhmolpilli
The ancient Mexicans counted their years by means of four signs combined with thirteen numbers, thus obtaining periods of 52 years,[3] which are commonly known as Xiuhmolpilli, a popular but incorrect generic name; the most correct Nahuatl word for this cycle is Xiuhnelpilli.[4] The table with the current years:
Tlalpilli Tochtli
Tlalpilli Acatl
Tlalpilli Tecpatl
Tlalpilli Calli
1 tochtli / 1974
1 acatl / 1987
1 tecpatl / 2000
1 calli / 2013
2 acatl / 1975
2 tecpatl / 1988
2 calli / 2001
2 tochtli / 2014
3 tecpatl / 1976
3 calli / 1989
3 tochtli / 2002
3 acatl / 2015
4 calli / 1977
4 tochtli / 1990
4 acatl / 2003
4 tecpatl / 2016
5 tochtli / 1978
5 acatl / 1991
5 tecpatl / 2004
5 calli / 2017
6 acatl / 1979
6 tecpatl / 1992
6 calli / 2005
6 tochtli / 2018
7 tecpatl / 1980
7 calli / 1993
7 tochtli / 2006
7 acatl / 2019
8 calli / 1981
8 tochtli / 1994
8 acatl / 2007
8 tecpatl / 2020
9 tochtli / 1982
9 acatl / 1995
9 tecpatl / 2008
9 calli / 2021
10 acatl / 1983
10 tecpatl / 1996
10 calli / 2009
10 tochtli / 2022
11 tecpatl / 1984
11 calli / 1997
11 tochtli / 2010
11 acatl / 2023
12 calli / 1985
12 tochtli / 1998
12 acatl / 2011
12 tecpatl / 2024
13 tochtli / 1986
13 acatl / 1999
13 tecpatl / 2012
13 calli / 2025
Reconstruction of the Solar calendar
For many centuries scholars had tried to reconstruct the Calendar. A widely accepted version was proposed by Professor Rafael Tena of the Instituto Nacional de Antropología e Historia,[5] based on the studies of Sahagún and Alfonso Caso of the National Autonomous University of Mexico. His correlation argues that the first day of the Mexica year was February 13 of the old Julian calendar or February 23 of the current Gregorian calendar.
Using the same count, it has been the date of the birth of Huitzilopochtli, the end of the year and a cycle or "Tie of the Years", and the New Fire Ceremony, day-sign 1 Tecpatl of the year 2 Acatl,[6] corresponding to the date February 22. A correlation by independent researcher Ruben Ochoa interprets pre-Columbian codices, to reconstruct the calendar, while ignoring most primary colonial sources that contradict this idea, using a method that proposes to connect the year count to the vernal equinox and placing the first day of the year on the first day after the equinox.[7]
In this regard, José Genaro Emiliano Medina Ramos, a senior native nahua philosopher from San Lucas Atzala in the state of Puebla, proposes a multidisciplinary calendar reconstruction in náhuatl (‘centro de Puebla’ variant) according with his own nahua cosmosvision;[8] and relying precisely on Ochoa's smart correlation and on Tena's presuppositions as well. His proposal was translated to Spanish and English, and codified as an academic webpage in 2023.[9]
^Hill Boone, Elizabeth (2016). Ciclos de tiempo y significado en los libros mexicanos del destino [Cycles of time and meaning in the Mexican books of destiny]. Mexico City: Fondo de Cultura Económica. ISBN9786071635020.
^Beuchat, Henri (1918). Manual de arqueología americana [Manual of American Archeology]. Madrid: Daniel Jorro. pp. 349–352.
Aguilar-Moreno, Manuel (n.d.). "Aztec Art"(PDF). Aztec Art and Architecture. Foundation for the Advancement of Mesoamerican Studies, Inc. (FAMSI). Archived from the original(PDF) on 2008-06-25. Retrieved 2008-05-14.{{cite web}}: CS1 maint: year (link)
Clavigero, Francesco Saverio (1807) [1787]. The history of Mexico. Collected from Spanish and Mexican historians, from manuscripts, and ancient paintings of the Indians. Illustrated by charts, and other copper plates. To which are added, critical dissertations on the land, the animals, and inhabitants of Mexico, 2 vols. Translated from the original Italian, by Charles Cullen, Esq. (2nd ed.). London: J. Johnson. OCLC54014738.