Nearly 500 years after the Spanish conquered their mighty empire, the Aztecs are often remembered today for their major capital, Tenochtitlan, as well as being fierce conquerors of the Valley of Mexico who often engaged in human sacrifice rituals. Unlike the Maya, the Aztecs are not widely viewed or remembered with nuance, in part because their own leader burned extant Aztec writings and rewrote a mythologized history explaining his empire’s dominance less than a century before the Spanish arrived. Naturally, Cortes and other Spaniards depicted the Aztecs as savages greatly in need of conversion to Catholicism. While the Maya are remembered for their astronomy, numeral system, and calendar, the Aztecs have primarily been remembered in a far narrower way, despite continuing to be a source of pride to Mexicans through the centuries.

For the Aztec, astronomy was not a purely scientific pursuit but intimately linked to religious, mythological, and ideological elements that were of the highest importance. The celestial realm held a sacred nature, as did the many gods and goddesses that dwelt there, so for all Mesoamerican cultures, astronomy was a fundamental part of their daily lives. Thus, astronomy was present in their calendars, religion, and even agriculture, and in close relation to astronomy, the concept of time was also an essential part of their worldview. The Aztec recorded many of the astronomical events they observed in codices and hieroglyphic inscriptions, but the main evidence of their deep astronomical knowledge comes from their calendar system. This information was then used to plan the orientation of buildings and ceremonial centers, which were aligned to sunrises or sunsets corresponding to special dates, such as solstices or equinoxes. Observational calendars were also used to schedule agricultural activities, as well as rituals, festivals, and celebrations, on an annual cycle.