aztec calendar stone

222 years ago today (December 17, 1790) the Aztec Calendar Stone was discovered in Mexico City’s Zócalo.

Workers repairing the cathedral in the city’s main square were excavating when they found the 24 ton stone carving. It was soon mounted on the wall of the cathedral where it remained until the late 1890’s when it was transferred to an archeology museum.

In 1964, the Mexica Sun Stone was moved to Mexico’s National Museum of Anthropology in Chapultepec Park.

Archaeologists believe the Stone of the Sun was carved in 1479, just 40 years before contact with the Spanish.

 1790 – Discovery of the Aztec calendar stone.
The Aztec calendar stone, Sun Stone, or Stone of the Five Eras is a late post-classic Mexica sculpture housed in the National Anthropology Museum in Mexico City, and is perhaps the most famous work of Aztec sculpture.

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The Aztec Calendar

The Aztecs had two calendar cycles, one 365 days and based on the sun, and one 260 days and based on ritual. They aligned every 52 years.

An engraving of an Aztec calendar can be found in the 1699 world chronicle Giro del mondo (Mirror of the World). Volume 6 is entirely dedicated to Mexico and contains information from pre-Conquest sources.

By the way, the famous “Aztec Calendar Stone” isn’t actually a calendar; it’s a sacrificial altar that the Aztecs called a cuauhxicalli, or eagle vessel. Shown here is the first European image of the Calendar Stone, created just months after the massive carving was unearthed in 1790, more than two centuries after being buried by the Spanish.

The Aztecs were expert astronomers. There’s disagreement about how they accounted for the fact that there are more than 365 days in each solar year—365.2422, to be exact. We account for it with our leap years, which bring us the extra-special February 29.  

Engraving [GIF-ed] of an Aztec calendar in Giro del mondo…, vol. 6. Engraving of the Aztec Calendar Stone by Francisco de Agüera in Antonio de León y Gama, Descripción histórica y cronológica de las dos piedras… Both prints: The Getty Research Institute