Teotihuacan's Pyramid of the Moon is Actually Aligned with the Solstice Sun

A new study reveals that the Pyramid of the Moon at Teotihuacan, Mexico, marks the astronomical orientation axis of the ancient city. The research team, coordinated by Ismael Arturo Montero García, has verified that the vertices of the pyramid align to the northeast with the summer solstice sunrise and to the southwest with the winter solstice sunset. This groundbreaking discovery suggests that the Teotihuacans intentionally designed the city to highlight these significant solar events.

The archaeoastronomy specialists from the University of Tepeyac (UT) and the National School of Anthropology and History (ENAH) found that on the longest day of the year, the sun rises over the Xihuingo volcano, which functioned as an observatory to calibrate the calendar, and sets behind Maninal Hill to the west, states an INAH report.

This alignment indicates the Teotihuacans' advanced understanding of celestial mechanics and their integration of natural landscape features into their urban planning.

The Pyramid of the Moon, located at the end of the Causeway of the Dead, served as the focal point of this astronomical axis.

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View to the south from the Pyramid of the Moon, the path of the red line passes over the top of the Pyramid of the Sun. (Arturo Montero, 2006/INAH)

A Shift in Perspective

This new model shifts the focus from the previously emphasized Pyramid of the Sun to the Pyramid of the Moon, asserting that the latter is the most important structure in Teotihuacan.

The volume of the Pyramid of the Moon provided a proportional relationship with the surrounding space, creating a frontal effect that defined the homonymous plaza. This strategic placement contained the visual axis and complemented the facades of other buildings in the city, says Montero García according to the INAH release.

García explains that the pyramid's east and west sides align with specific dates related to the solstices. By drawing perpendicular lines from these sides, the team identified alignments for October 29 and February 12 on the east side, and April 29 and August 13 on the west side. These dates are significant in the pre-Hispanic worldview, as they are 52 days before and after the solstices, corresponding with the 52-year cycle of the New Fire ceremony.

Aerial view of the Pyramid of the Moon at the end of the Causeway of the Dead. (Mauricio Marat/ INAH)

Confirmations and Debates

Photographic and video evidence supporting these hypotheses were obtained through drone flights conducted by independent professional Rafael Morales Orozco, director of the documentary series “Relatando Historias.” Geographer Anabell Pérez Flores is developing digital models to illustrate the research findings further.

Live Science reports that the team's research suggests the Pyramid of the Moon's alignment influenced the orientation of the entire city. Archaeoastronomer Aarón González Benítez of ENAH notes that the city’s reticular design replicates the pyramid's solar orientations, indicating a comprehensive urban planning approach based on astronomical principles.

However, not all experts agree with this assessment. Ivan Sprajc, head of the Institute of Anthropological and Spatial Studies at the Slovenian Academy of Sciences and Arts, argues that it is difficult to believe the city was built with the solstice alignment in mind, noting modifications to the pyramid during its construction phases. Steven Gullberg, a professor of cultural astronomy at the University of Oklahoma, acknowledges the team's findings but anticipates a lively debate among specialists in the field, records Live Science.

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Cultural Significance

The research also highlights an interesting cultural aspect regarding the pyramid’s name. González Benítez points out that the structure was named the "Pyramid of the Moon" by the Mexica people, who founded the Aztec Empire after the city was abandoned. The original name given by Teotihuacan’s inhabitants remains unknown. Intriguingly, the team’s research suggests that the Pyramid of the Sun aligns with lunar standstills rather than solar events, adding another layer of complexity to Teotihuacan’s astronomical architecture.

The team's findings will be compiled in a forthcoming book and have already been featured in a documentary. Additionally, to disseminate their research, Arturo Montero will present a lecture titled “The Zenith Passage of the Sun between Teotihuacan and the AIFA” and conduct an astronomical workshop on sunspots at the Santa Lucía Quinametzin Paleontological Museum.

Top image: The Sun rises behind the El Xihuingo volcano during the summer solstice.                Source: Rafael Morales Orozco, retouching by Arturo Montero/ INAH

By Gary Manners