Aztec Calendar Stone

Sculpture; Mexico City, Mexico

File:Aztec calendar stone in National Museum of Anthropology, Mexico City.jpg(Aztec Sun Stone; courtesy of Wikipedia)

The Aztec Calendar Stone, otherwise colloquially known as the Mexica Sun Stone or historically known as the Cuauhxicalli Eagle Bowl, is a giant circular stone sculpture about 12 feet in diameter. The stone it’s carved on is approximately 4 feet thick, and the entire disk weighs about 24 tons. This particular calendar was made from basalt, which is solidified lava. This is indicative of the amount of volcanoes near where this calendar was made.

In fact, the Aztecs used basalt for more than just carving this monolithic structure; they used basalt to build buildings and make grinding stones. Stones like this were extremely important to the Aztecs because they believed that stones were “bones of the earth.” Some say that the Aztecs never “emerge[d] from the stone age.” Especially useful to the Aztecs were stones like basalt: the ones that came from the numerous volcanoes they had around. For example, they used obsidian for weapons because it was so strong and easily split to make sharp blades. Stone was something readily accessible to the Aztecs where they were, and they often utilized that because metals hadn’t become as big of a deal where they were.

In the center of the circle is a carving of the Aztec sun god, Tonatiuh. The sun god appears to be holding two human hearts, and his tongue is sharp as the ritual blades used for sacrifices are. One of the beliefs the Aztecs had was that blood was needed for the sun to keep shining. The story goes that Tonatiuh was reborn every morning and died every night, making a grueling trip across the sky every day. To keep him healthy, he needed blood and human hearts. This was the cause for human sacrifices to the sun god.

(Tonatiuh and the four Suns; courtesy of

Surrounding the sun god on the Aztec Calendar Stone are pictographic representations of the eras that came before. The Aztecs believed that there have been several historical ages, which are known as Suns. Before now, there were four (representing earth/jaguars, wind, fire/rain, and water), all of which were destroyed, and now we are living in the fifth Sun, which is the Sun of Movement.

Beyond the four pictographs are concentric circles; some have pictures showing time and some have hieroglyphic writing about time on them. The Aztec calendar system was complex. There were two calendars operating simutaneously: the Xiuhpohualli and the Tonalpohualli.

Aztec calendar stone picture
(Color depiction of the Calendar Stone; courtesy of

The Xiuhpohualli was more like our traditional Gregorian calendar; it counted a year as 365 days and used the sun’s movements to track the length of a day. There were five “leftover” days, which were considered very unlucky; the Aztecs thought disasters were more likely to happen then. The Tonalpohualli, on the other hand, was known as the religious or sacred calendar. It was separated equally between all of the gods, so that the Aztecs would know how much time to spend with each god so things would stay fair. The two calendars were used together in a way that the only time a date was repeated was once every 52 years. On that day, there was a festival thrown known as the New Fire Festival because the Aztecs thought that this day could be the one where a new Sun era began and the current one was destroyed.

Aztec Calendar
(The 20 day signs of the Tonalpohualli; courtesy of

On the Aztec Calendar Stone, the first circle outside of the four Suns shows the 20 days of the Aztec month followed by the five unlucky days. The circle around that one shows five-day-long weeks. Outside of that circle are snakes that represent the start of a new cycle of 52 years.

Other civilizations also used a multiple-calendar system to keep track of time. For example, the Maya had a calendar system very similar to the Aztecs. They had one 365-day calendar (called the Haab) that was the “regular” calendar and another calendar that had 260 days (called the Tzolkin) that was sacred, set up like the Aztec Calendar was. They, too, had a cycle that lasted 52 years. The Zapotecs and Mixtecs also had this same calendar system, so it’s apparent the idea behind the calendar stayed relatively consistent throughout early Mesoamerica.

Aztec and Mayan Calendars
(Comparison of the Aztec Calendar with the Mayan Calendar; courtesy of

Although the Aztec Calendar Stone shows the incredible precision of the Aztecs and their ability to use astronomy to determine the year length and the solar patterns to figure out a day length, archaeologists still don’t really know what the Aztecs used the Calendar Stone for. The fact that one of the prime focuses of the disk is the sun god supports the idea that perhaps the Calendar Stone was used as a religious decoration or some type of sacrificial alter. However, holes were found on the outer rim of the Calendar Stone, which pegs could have fit in, supporting the notion that the Calendar Stone may have been used as a sundial of sorts. The fact is, though, that while people still have ideas about what the Calendar Stone was used for, we still just don’t know.

(The 8 holes on the edge of the disk; courtesy of

The giant sculpture was found by accident in the main square of Mexico City, Mexico, in December of 1790 while renovations were being done in that part of the city. It’s believed that after the Aztec Empire was destroyed, Spaniards took the Aztec Calendar Stone and buried it in the square; then, they built a cathedral on the other side of the plaza to further hamper the indigenous religions. Immediately after the stone’s discovery, it was embedded into the wall of the Western Tower of the Metropolitan Cathedral until 1885, when it was taken to the National Museum of Archaeology and History under the command of President Porfirio Diaz.

The Aztec Calendar Stone is an extremely interesting object. It shows the Aztec’s amazing ability to understand movement of the stars and the sun to figure out specific lengths of time. The nearly perfect circle shows the Aztec’s advanced geometrical skills. The depictions of gods and pictographs show the Aztec’s devotion to their gods. This immense piece of stone is obviously an extremely important object that tells multiple different stories about the Aztecs.

Alfred, Randy. “Dec. 17, 1790: Aztec Calendar Stone Discovered.” Conde Nast Digital, 17 Dec. 2008. Web. 15 Apr. 2013.

“Aztec Calendar (chronology).” Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 13 Apr. 2013.

“The Aztec – Introduction.” N.p., n.d. Web. 13 Apr. 2013.

“Aztec Calendar Stone.” N.p., n.d. Web. 13 Apr. 2013.

“Aztec Calendar Stone.” Token Rock. N.p., n.d. Web. 13 Apr. 2013.

Lienhard, John H. “No. 1086: An Obsession with Obsidian.” Engines of Our Ingenuity. N.p., n.d. Web. 16 Apr. 2013.

“Mayan Calendars.” Yucatan Adventures. N.p., n.d. Web. 16 Apr. 2013.

“Mesoamerican Writing Systems.” Ancient Scripts. N.p., n.d. Web. 16 Apr. 2013.

“Tonatiuh (Aztec God).” Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 13 Apr. 2013.

“Tonatiuh.” Aztec Calendar. N.p., n.d. Web. 13 Apr. 2013.

Van, Tuerenhout Dirk R. “Material Culture: Stone Tool Production.” The Aztecs: New Perspectives. Santa Barbara, CA: ABC-CLIO, 2005. 217-18. Print.


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