Ацтек күнтізбесінің жүйесі

Calendar system that was used by the Aztecs

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, also called the calendar stone, is on display at the National Museum of Anthropology in Mexico City. The 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.

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.

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, 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, 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. 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; 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.