Frequently Asked Questions
Q: Is the correlation used by AztecCalendar.com the correct one?
A: As a default, AztecCalendar.com uses the Alfonso Caso correlation, that results in what is regarded by most scientists as the authentic alignment of pre-conquest mesoamerican daycount or tonalpohualli. However, your local current day shaman or daykeeper may not agree. On the Settings page, you can change the correlation settings.
Q: Did the pre-conquest Aztec Calendar have leap years?
A: No, it didn't.
No pre-conquest mesoamerican calendar ever used leap years. This means that the agricultural implications of the month names gradually slipped away from the periods of the solar year they may originally have designated. Astronomical corections were known and written down, but the calendar itself was not changed.
See: Munro S. Edmonson, "Book of the Year: Middle American Calendrical Systems". University of Utah Press, 1988.
Q: Some authors claim the Aztec Calendar uses leap years, are they wrong?
A: Maybe, but not necessarily.
After the conquest many mesoamerican calendars got fixed to the Julian calendar as used by the Spaniards. Since the Julian (and later the Gregorian) calendar has leap years this effectively introduced leap years to the Aztec Calendar. For the Aztec Calendar this happened around the year 1548. These post-conquest systems are not implemented on this site.
Q: Did the Aztecs have a Long Count, like the Maya did?
A: In order to keep up with astronomical events, the Mexica must have kept an accurate count of days, so I regard it likely they did. It might have been similar to the one used by the Maya. However, no direct evidence for an Aztec Long Count exists.
Q: Why didn't the world end on December 21, 2012?
A: The Maya never claimed the world would end on that day. However, according Mayan belief, December 21, 2012, the end of the 13th baktun (a 144.000 day period), Long Count date 13.0.0.0.0, strongly signified a new beginning, but not the end of the world by itself. According to the Maya, the end of the previous world and the beginning our current era was on a day 4-Xochitl (Ahau) with the Long Count date 13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.13.0.0.0.0, so on a date somewhat comparable to December 21, 2012. Falling on the winter solstice, the start of the return of the summer, December 21, 2012 emphasized the quality of a new beginning even more.
According to Aztec mythology, the current world is likely to end on a day 4-Ollin.