Ancient Mesoamerican ‘Pyramid of the Moon’ May Align With Summer and Winter Solstices

Thirty miles northeast of Mexico City, in the ancient Mesoamerican city of Teotihuacán, is a huge monument known as the “Pyramid of the Moon.” Recently, a team of archaeoastronomers proposed that something interesting occurs at this site two days a year: on the summer and winter solstices.

At the summer solstice, the sun rises over the Xihuingo volcano, which aligns with the pyramid’s northeast vertex. And during the winter solstice, the sun sets at the monument’s southwesternmost point, behind the nearby Moctezuma Peak and Chiconautla Hill.

Researchers released their observations, gathered from a series of measurements that included drone flights, in a statement on July 12.

Settled as early as 400 B.C.E., the ancient city of Teotihuacán became central Mexico’s economic and religious hub in pre-Aztec times. It had a wide central street called the “Avenue of the Dead” or “Causeway of the Dead,” and the north side of this route ended at the Pyramid of the Moon, directly aligning with the monument’s main stairs.

“It is thanks to the masterful design of this causeway that when you walk along [the Avenue of the Dead], the observer’s vision is guided by the architectural landscape towards the Pyramid of the Moon,” Aarón González Benítez, a member of the research team and an archaeoastronomer at the National School of Anthropology and History in Mexico, tells Newsweek’s Aristos Georgiou.

Both the Avenue of the Dead and the Pyramid of the Moon were built between 100 and 350 C.E. Because of Teotihuacán’s layout, the pyramid’s proposed astronomical orientation would have had implications for the alignment of the entire city.

“The city of Teotihuacán stands out among other things for its magnificent reticular design, and if the solar orientations of the Pyramid of the Moon determined the orientation of the city, the other monuments that are parallel to this great building would be following and replicating the same canonical orientation,” González Benítez tells Live Science’s Owen Jarus.

Archaeological remains suggest the people of Teotihuacán may have frequented both the Xihuingo volcano and Chiconautla Hill as astronomical observatories, which makes the sun’s alignment during the solstices even more intruiging to the team, according to a short documentary about the research.

To ancient Mesoamerican people, the sun—especially its solstices and equinoxes—was foundational in their understanding of the world, writes Newsweek. In fact, earlier research focused on the astronomical alignments of Teotihuacán’s largest structure, the Pyramid of the Sun (also built between 100 and 350 C.E.).

The Moon and the Sun in Teotihuacan, new notes to its archaeoastronomy

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The team’s conclusions highlight an ostensible contradiction—that the solstices align with the Pyramid of the Moon as opposed to the Pyramid of the Sun. However, this is explained by the fact that the people of Teotihuacán did not use these names—they were assigned to the monuments by the Mexica people, who founded the Aztec Empire centuries later. Researchers still don’t know what the pyramids’ original names were.

The Pyramid of the Sun might actually have architectural ties to the moon—the researchers observed that its northeast and southwest vertices align with lunar standstills or “lunistices,” when the moon reaches its northernmost or southernmost point during a lunar month. If confirmed, this wouldn’t be the first time an ancient civilization aligned its structures with lunistices—recently, researchers suggested Stonehenge may also have a connection to major lunar standstills.

Not all experts agree with the proposal, however. Ivan Sprajc, head of the Institute of Anthropological and Spatial Studies at the Slovenian Academy of Sciences and Arts, points out to Live Science that the Pyramid of the Moon’s structure was changed during its construction, and it originally had a different orientation than the current one. This, he adds, casts doubt on the astronomical layout of the city.

The researchers, however, say in the statement that the Pyramid of the Moon is evidence the people of Teotihuacán had a deep knowledge of celestial mechanics.

Margherita Bassi | READ MORE

Margherita Bassi is a freelance journalist and trilingual storyteller. Her work has appeared in publications including BBC Travel, Discover magazine, Live Science, Atlas Obscura and Hidden Compass.