Aztec zodiac signs

The 20 day signs

The solar year and the 52-year cycle

Alongside the 260-day count ran the xiuhpohualli, a 365-day solar year of eighteen 20-day “months” (veintenas), each with its own festival, followed by five unlucky days called nemontemi. The two counts return to the same combination every 52 years, a period called the xiuhmolpilli (“binding of the years”). At its end the Aztecs held the New Fire Ceremony, extinguishing every fire and relighting them from a single flame; the last was celebrated in 1507.

How it works

Like the Maya tzolk’in, the Aztec tonalpohualli (“count of days”) combines 13 numbers with 20 signs. Each day had a patron deity, and priests consulted the tonalamatl (“book of days”) to name children and choose dates. The famous Aztec Sun Stone shows the 20 day signs in a ring around its center.

Correlation

The calculator aligns the count so that the fall of Tenochtitlan, August 13, 1521 (Julian calendar), is 1 Coatl, following Alfonso Caso; this matches the Maya count under the GMT correlation.

Aztec “zodiac” charts

As with the Maya, month-by-month “Aztec zodiac” charts are modern. The authentic birth sign is the day sign. Compare the Maya day signs.

Sources

• Wikipedia: Tonalpohualli
• Wikipedia: Aztec calendar stone