If you look at the astronomy of the Aztecs, you will find something quite unusual. While for many other civilizations the night sky has been a source of stability and unchanging harmony, Aztecs were concerned about a lack of stability and the potential destruction of the world coming from the sky.
The Aztecs used a complex calendar system characteristic of Mesoamerican civilizations. It combined a count of 365 days based on the solar year with a separate calendar of 260 days based on various rituals. Every 52 years, both calendars would overlap and a new cycle would commence.
Unlike other civilizations, such as the Mayans, the Aztec seriously considered the possibility that the world could be destroyed and recreated at the end of such a 52-year cycle. Such cosmological understanding has far-reaching cultural and social consequences. While the notion of the world’s destruction (and recreation) is found in other cosmologies as well – whether it is in ancient India or in medieval Christianity – having such a recurring danger in periods comparable with human life spans is quite extraordinary.
Historians of Aztec astronomy nowadays speak of entire ritual landscapes in which not only cities were planned according to astronomical alignments, but in which the very location of major cities had been determined by their significance for rituals that were guided by astronomical observations.
By interpreting the complexity of their calendar as the expression of a world view, in which different deities act in different ways, often opposing each other and leaving the fate of humanity depending on the outcome of their efforts, the Aztec regarded each day as being dominated by different, potentially conflicting meanings given by the various calendar counts. At the centre of their cosmology, however, stood the sun, famously represented in the Aztec Calendar Stone.
For the Aztecs, it was the fifth sun, following the earlier four suns having come to an end with various destructions of the world. This sun had itself come into existence as the result of a god sacrificing himself for humanity, a sacrifice that in itself was mandating human sacrifice to the sun, as well as a life that needed to be lived to prevent the gods destroying the world again.
For the Aztecs, like for many other civilizations, astronomy was a study closely associated with religious significance and a strong moral code of behavior. Aztec astronomy also played an important role in later history in relation to the emancipation of Mexico from Spanish colonial rule.
After the Aztec Calendar Stone was discovered during construction works in Mexico City in 1792, the Spanish American astronomer and polymath Antonio de León y Gama (1735-1802) became the first scholar to try to understand the astronomical system represented in the calendar stone. In order to solve the puzzles he encountered in the process he had to study a large number of sources from different Mesoamerican civilizations.
What surprised him was how little understanding of those cultures the existing European literature on the topic demonstrated. For de León y Gama, this caused a shift in perspective, and he saw himself no longer at the margins of European civilization, but in a unique position in universal history. He argued that only Mexicans could properly understand Aztec culture, as Mexico combined European and Aztec heritage. Around 1800, his claim that the Aztecs had been on the same cultural level as the great civilizations of ancient Greece and Egypt provoked much controversy. However, supported by good arguments from the study of Aztec astronomy this claim helped establish a Mexican identity independent of the Spanish mother country in the 19th century.
The Aztec Calendar Stone remains one of the central icons of Mexican culture.