The Aztec or Mexica calendar is the calendrical system used by the Aztecs as well as other Pre-Columbian peoples of central Mexico. It is one of the Mesoamerican calendars, sharing the basic structure of calendars from throughout the region. 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 (year count), and a 260-day ritual cycle called (day count). These two cycles together form a 52-year "century", sometimes called the "calendar round". The is considered to be the agricultural calendar, since it is based on the sun, and the is considered to be the sacred calendar.

Tōnalpōhualli, Aztec Sacred Calendar The ("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.

There is some variation in the way the day signs were drawn or carved. Those here were taken from the .

Image Nahuatl name Pronunciation English translation Direction CrocodileAlligatorCaimanCrocodilian MonsterDragon East Wind North House West Lizard South SerpentSnake East Death North DeerAnimal West Rabbit South Water East Dog North Image Nahuatl name Pronunciation English translation Direction Monkey West Grass South Reed East OcelotJaguar North Eagle West Vulture South MovementQuakeEarthquake East FlintFlint Knife North Rain West Flower South Wind and Rain are represented by images of their associated gods, and 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.

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 , using a Spanish term derived from "thirteen" (just as the Spanish term "dozen" is derived from "twelve"). The original Nahuatl term was "in cencalli tonalli" (a family of days), according to Book IV of the Florentine Codex.

Each is named according to the calendar date of the first day of the 13 days in that . In addition, each of the twenty in the 260-day cycle had its own tutelary deity:

Deity Deity 1 Crocodile 1 Monkey 1 Jaguar 1 Lizard 1 Deer 1 Quake 1 Flower 1 Dog 1 Reed 1 House 1 Death 1 Vulture 1 Rain 1 Water 1 Grass 1 Wind 1 Snake 1 Eagle 1 Flint 1 Rabbit

Xihuitl, Aztec Solar Calendar

is the Aztec year () count (). One year consists of 360 named days and 5 nameless (). 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 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 .

Each 20-day period started on (Crocodile) for which a festival was held. The eighteen are listed below. The dates are from early eyewitnesses; each wrote what they saw. 's date precedes the observations of 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 after the Mexica defeat.

Veintenas of the xiuhpōhualli # Glyph Name Gregorian range Presiding deities Durán Sahagún 1 ātl cāhualo (“the water ceases”) cuahuitl ēhua (“the trees rise”) Mar 01–Mar 20 Feb 02–Feb 21 Water gods 2 tlācaxīpēhualiztli (“flaying of men”) Mar 21–Apr 09 Feb 22–Mar 13 Xipe Totec 3 tōzōztōntli (“lesser vigil”) Apr 10–Apr 29 Mar 14–Apr 02 Tlaloc 4 huēyi tōzōztli (“greater vigil”) Apr 30–May 19 Apr 03–Apr 22 Cinteotl 5 toxcatl (“dryness”) May 20–Jun 08 Apr 23–May 12 Tezcatlipoca 6 etzalcualiztli (“eating of cooked maize and beans”) Jun 09–Jun 28 May 13–Jun 01 Tlaloque 7 tēcuilhuitōntli (“lesser feast day”) Jun 29–Jul 18 Jun 02–Jun 21 Huixtocihuatl 8 huēyi tēcuilhuitōntli (“greater feast day”) Jul 19–Aug 07 Jun 22–Jul 11 Xilonen 9 tlaxōchimaco (“giving of flowers”) miccāilhuitōntli (“lesser feast day of the dead”) Aug 08–Aug 27 Jul 12–Jul 31 Huitzilopochtli 10 xocotl huetzi (“the xocotl falls”) huēyi miccāilhuitl (“greater feast day of the dead”) Aug 28–Sep 16 Aug 01–Aug 20 Xiuhtecuhtli 11 ochpaniztli (“sweeping”) Sep 17–Oct 06 Aug 21–Sep 09 Teteo Innan 12 teōtlehco (“the gods arrive”) Oct 07–Oct 26 Sep 10–Sep 29 All the gods 13 tepēilhuitl (“feast day of mountains”) Oct 27–Nov 15 Sep 30–Oct 19 Mountains 14 quechōlli (“roseate spoonbill”) Nov 16–Dec 05 Oct 20–Nov 8 Mixcoatl 15 panquetzaliztli (“raising of banners”) Dec 06–Dec 25 Nov 09–Nov 28 Huitzilopochtli 16 ātemoztli (“descent of water”) Dec 26–Jan 14 Nov 29–Dec 18 Rain gods 17 tititl (“tightening,” “contraction”) Jan 15–Feb 03 Dec 19–Jan 07 Tonan 18 izcalli (“offshoot,” “bud”) Feb 04–Feb 23 Jan 08–Jan 27 Xiuhtecuhtli – nēmontēmi (“they fill up in vain”);Not a veintena, 5-day complementary period Feb 24–Feb 28 Jan 28–Feb 01 None

Xiuhmolpilli The Mexica counted their years by means of four signs combined with thirteen numbers, thus obtaining periods of 52 years,Tena, 2008: 103. There he shows us a table. which are commonly known as Xiuhmolpilli, a popular but incorrect generic name; the most correct Nahuatl word for this cycle is Xiuhnelpilli.Tena, 2008:9. The table with the current years: Tlalpilli TochtliTlalpilli AcatlTlalpilli TecpatlTlalpilli Calli1 tochtli / 19741 acatl / 19871 tecpatl / 20001 calli / 20132 acatl / 19752 tecpatl / 19882 calli / 20012 tochtli / 20143 tecpatl / 19763 calli / 19893 tochtli / 20023 acatl / 20154 calli / 19774 tochtli / 19904 acatl / 20034 tecpatl / 20165 tochtli / 19785 acatl / 19915 tecpatl / 20045 calli / 20176 acatl / 19796 tecpatl / 19926 calli / 20056 tochtli / 20187 tecpatl / 19807 calli / 19937 tochtli / 20067 acatl / 20198 calli / 19818 tochtli / 19948 acatl / 20078 tecpatl / 20209 tochtli / 19829 acatl / 19959 tecpatl / 20089 calli / 202110 acatl / 198310 tecpatl / 199610 calli / 200910 tochtli / 202211 tecpatl / 198411 calli / 199711 tochtli / 201011 acatl / 202312 calli / 198512 tochtli / 199812 acatl / 201112 tecpatl / 202413 tochtli / 198613 acatl / 199913 tecpatl / 201213 calli / 2025

Reconstruction of the Calendar

In the last century scholars have made multiple models reconstructing the Calendar.

The Xiuhmachiotl is a contemporary digital reconstruction project that presents multiple Mesoamerican calendrical systems in an integrated interface. Its implementation combines a 260-day Tonalpohualli, a 365-day Xiuhpohualli, a Venus-focused Citlalpohualli, a nine-day Night Lord sequence, lunar and Long Count displays, and additional astronomical visualisation tools. The project distinguishes between reconstructed ceremonial calendar coordinates, arithmetic mean-cycle models, and bounded ephemeris-derived planetary-event data.

Another version was proposed by Professor of the ,The Mexica Calendar and the Chronography, Rafael Tena. INAH-CONACULTA. 2008 based on the studies of and 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 , the end of the year and a cycle or "Tie of the Years", and the New Fire Ceremony, day-sign of the year ,Crónica Mexicayotl, Fernando Alvarado Tezozomoc p 36 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.

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; and relying on Ochoa's correlation and on Tena's presuppositions as well. His proposal was translated to Spanish and English, and codified as an academic webpage in 2023.

Unfortunately, both Ochoa and Medina correlations go against strong evidence pointed out by scholars about the Mexica start of day and of the lack of a leap day in all Mesoamerican calendars. In this regard, some Mexican groups such as Kaltonak, are proposing a reconstruction of the calendar based on astronomical, archaeological and historical evidence.

See also Aztec New Year Maya calendar Mesoamerican calendars Muisca calendar

Notes

References