Aztec Calendar: It Is More Than What We Know

The Sun Stone is one of the most famous Mesoamerican sculptures, yet this mysterious Aztec calendar harbors many secrets. Recent studies leave us baffled. Read on to find out what expert theorists suggest.

Apr 16, 2020By Mia Forbes, BA in Classics
Aztec Calendar, closeup view
Aztec Calendar, closeup view

Since its discovery in 1790, the Aztec Calendar (or Sun Stone) has intrigued archaeologists, historians and conspiracy theorists alike. Various interpretations have been put forward about its use and until recently, almost everyone has agreed that it was some form of calendar. But new research has brought to light facts that suggest otherwise. Read on to discover more about this mysterious stone, and why it may not be all it seems.


What Is The Aztec Calendar?

Aztec Calendar from the Casanola archives, 1913
The discovery of the Aztec Calendar, Casasola Archive, 1913

The Aztec Calendar, also known as the Sun Stone, is a monumental sculpture which weighs a mammoth 24,590kg and slightly over 3ft thick. The circular front panel, which has a huge diameter of around 11.5ft, displays eight concentric circles, on which appear various symbols. These represent a selection of native animals, like crocodiles, jaguars and eagles; natural elements, including wind, water and rain; some rudimentary markers of civilization, such as houses; shared features of humanity, including movement and death.

At the very center is the haunting face of a deity or a monster. Although there are debates about who (or what) is depicted, most commentators believe that it shows the sun god Tonatiuh, one of the most important deities in the Aztec pantheon. What makes the image particularly ominous is that the figure is shown baring its dagger-like tongue and clutching a human heart in its claws. This is thought to represent a demand for blood through human sacrifice. 


Who Made The Sun Stone?

 Portrait of Moctezuma, Jacob van Meurs, 1671, illustration, via The British Museum

Although it was previously thought that the monolith was carved in the late 15th century, new evidence and research have led scholars to different conclusions. It was found that a glyph in the central disk represented the name of the Aztec ruler, Moctezuma II, who ruled between 1502 and 1520. 

Although the Aztec Empire expanded to its peak under the reign of Moctezuma, it also eventually fell victim to the conquistadores, who took over the capital (now Mexico City) after the ruler himself was killed. The Spanish conquerors stated that the Sun Stone had been carved seven years before their invasion, in 1512, although given that they also claimed it took 10,000 men to drag the rock, their records should not be relied upon for accuracy.


The Discovery Of The Sun Stone

Venustiano Carranza with the Sun Stone in 1917
Mexican revolutionary leader, Venustiano Carranza with the Sun Stone, 1917, via Fototeco Nacional Mexico

When the Aztec empire was conquered by the Spanish in 1521, the conquistadores feared that their new subjects would continue practicing their terrifying religious rituals. In an attempt to put an end to the human sacrifices and sun worship, the Spaniards buried the Sun Stone upside down in the main square of what is now Mexico City. Over the centuries, the monolith became a ruin. Traces of paint have been discovered in the pores of the stone, showing that it was once brightly colored. Any hint of paint has been rubbed off over the course of time.

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Catedral Piedra del sol, 1950s
Catedral Piedra del sol, 1950s

In 1790,
the Aztec Calendar was unearthed by laborer’s working on the plumbing system in the city. The Spanish monarchs who then ruled Mexico displayed the Sun Stone on the side of the Metropolitan Cathedral, as evidence of the empire’s rich history. Beaten by the wind, rain, and the bullets of American soldiers, the stone was gradually eroded, until it was rehoused at the National Museum in 1885. 


The Legacy of the Sun Stone

 The Sun Stone in the National Anthropology Museum
The Sun Stone in the National Anthropology Museum

The Sun Stone has left a great legacy, not only in history and academia, but also in popular culture. 

Today, the Calendar is housed in Mexico’s National Anthropology Museum, where it attracts huge crowds of visitors, eager to figure out the mystery of the Sun Stone for themselves. So important is the monolith to Mexican culture, that its coins are based on the Calendar’s structure, with each denomination showing part of the circular design. 

In 2012, the Calendar once again came into the spotlight as conspiracy theorists claimed that it foretold the imminent end of the world. Luckily, the predictions were not accurate in this case, but the amount of attention the claim attracted demonstrates the long lasting influence of Aztec culture across the globe.


The Purpose of the Sun Stone

An example of a gourd bowl used to collect human entrails after sacrifice, via Fordham Univ.
An example of a gourd bowl used to collect human entrails after sacrifice, via Fordham Univ.

There is still no definitive answer to the mystery of why the monolith was made or what its purpose was. There are, however, several different interpretations. 

Until recently, it has been the widely held belief that the Sun Stone is a huge calendar, and thus it has become universally known as the Aztec Calendar. There are many good reasons to support this interpretation, not least that the concentric circles represent the days, ‘weeks’ and years of the Aztec calendar. 

Another interpretation is that the Sun Stone was actually used as a temalacatl, a gladiatorial platform. These were large stone structures to which a sacrificial victim would be tied, forced to fight and then finally killed, to placate the dreaded Tonatiuh. There are several examples of such stones in Mexican ruins; is it possible that the Sun Stone is one of them?

A third opinion is that the monolith was actually not designed to stand as it now does, with the panel facing forwards. Instead, some scholars believe that the circular side should be positioned upwards, and that the misnamed Calendar was actually a ceremonial altar, called a cuauhxicalli. These were vessels in which the entrails of sacrificial victims were collected and burnt. 

It’s now time to look at all the evidence, and decide which interpretation is the most credible.



Some of the symbols on the Aztec calendar, representing the day, the month and the solar year, via AztecCalendar
Some of the symbols on the Aztec calendar, representing the day, the month and the solar year, via AztecCalendar

The Sun Stone clearly displays the features of a calendar, with periods of time plotted out using symbols and sequences.
The Aztec year was made up of 260 days, divided into 13 months, each with 20 days. The concentric circles on the monolith display these divisions of time, adding weight to the argument that the Sun Stone was used as a chronological record. 

The circles emanating from the image of Tonatiuh represent the four previous Aztec eras, each of which was believed to have ended in apocalyptic catastrophes caused by wild beasts, hurricanes, fires and floods. The Aztecs believed that humanity was annihilated each time, and reborn at the start of the next era. The central circle is meant to represent the fifth age, in which the Aztecs who made it, were living. 

The chronological symbols and structure of the Sun Stone indicate that it was designed to show the passing of time, and therefore may have served as a calendar after all.



Close up Tonatiuh, Borgia Codex, via wikipedia
Close up Tonatiuh, Borgia Codex, via wikipedia

The Aztecs worshipped the sun as the source of life, and believed that Tonatiuh was the most important of all the gods. Although he provided warmth and sustenance, Tonatiuh also demanded blood. More specifically, human blood.

The Aztecs practiced the terrifying rite of human sacrifice in many gruesome ways, often involving the removal of the still-beating heart. Scholars believe that over the course of the 260 day year, hundreds of people would have been killed in this way. Victims were told that they would win a place besides the gods in the afterlife, although this may not have been much consolation as they were being tied to the sacrificial rock. 

The importance of religious sacrifice in Aztec culture may lead us to think that the Sun Stone had some symbolic or ceremonial purpose. 



Tonatiuh the Sun God, Borgia Codex, via WikiArt
Tonatiuh the Sun God, Borgia Codex, via WikiArt

Evidence from the Sun Stone suggests that its symbols may represent more than the passing of time or the importance of religion. In fact, the engravings may even be used to predict the future. In Aztec culture, the movement of the sun was used to foretell future events. Not only could Tonatiuh’s course be tracked to predict weather patterns and astronomical cycles, but they also believed that they could calculate the end of the world. 

It was thought that the present age would come to an end during a solar eclipse, when the sun’s light was blotted out and darkness descended. To avert this catastrophe, they attempted to win Tonatiuh’s favor with blood, performing sacrifices on certain days in the solar calendar. This suggests that the Sun Stone may have had both a chronological and ritual use: Aztec priests may have used it as a calendar to determine the day of sacrifice, and then as an altar at which to conduct the sacrifice itself. 



Map of the expansion of Aztec Empire, showing the areas conquered by the Aztec rulers, via reddit
Map of the expansion of Aztec Empire, showing the areas conquered by the Aztec rulers, via reddit

There is also a political aspect to the Sun Stone, which may have been made as a form of propaganda. 

Some scholars have argued that a series of small glyphs beside the previous eras’ sun symbols are designed to show the importance of Tenochtitlan, the Aztec state ruled by Moctezuma II. According to these historians, they represent not mythology but history. In particular, there are two bands which are thought to depict the victory of the Aztec armies over the combined forces of their enemies. Some even believe that the portrait at the center of the stone is meant to represent Moctezuma himself.

This evidence suggests that the Sun Stone was designed to reinforce the authority and power of human rulers as much as deities.



La Gran Tenochtitlan, Diego Rivera,1945 
La Gran Tenochtitlan, Diego Rivera,1945

Some final details from the Sun Stone indicate that there may also have been a geographical aspect to its design.

It has been suggested that the four arrows, which appear to either side, above and below the portrait of Tonatiuh, correspond to the four cardinal points. The Spanish conquistadores recorded that they had used local maps to navigate the empire; although none of these survive, it is clear that the Aztecs had an understanding of basic cartography and knew the importance of the cardinal directions. Like most old maps, their documents were oriented to the east, towards the rising sun.

The arrows engraved on the monolith may therefore indicate that the Sun Stone was used as a measure of space, as well as time.


The Answers

Human sacrifice in the Aztec civilization, via wikimedia
Human sacrifice in the Aztec civilization, via wikimedia

All of the evidence for the purpose and meaning of the Sun Stone points towards its importance as a symbol of Aztec culture. There is undoubtedly a religious aspect to the monolith, and its symbols strongly indicate that it could also be used to record time. Whether or not there is an overtly political element to its design, it is clear that such a monumental sculpture was designed to impress. 

It is up to you to make up your own mind about how exactly the Sun Stone was used: do you think it was really a calendar, or did it play a more gruesome role in Aztec sacrifices?

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By Mia ForbesBA in ClassicsMia is a contributing writer from London, with a passion for literature and history. She holds a BA in Classics from the University of Cambridge. Both at work and at home, Mia is surrounded by books, and enjoys writing about great works of fiction and poetry. Her first translation is due to be published next year.