Astronomy at the Peralta archaeological site, which appears to be designed based on celestial observation

09/06/2021

Monte Albán, Chichén Itzá, and Xochicalco are some of the most outstanding archaeological sites for their clear astronomical orientation; however, explorations in the sites of the so-called Bajío Tradition, in the state of Guanajuato, reveal that their peculiar architecture, determined by the "sunken patio", also possesses this type of values.

One of the first jobs to be done when arriving at a site is to place a compass where the pre-Hispanic foundations are located and measure their deviation with respect to the magnetic north, which is the direction marked by the pole of the same name. From this reading, the antiquity of the space can be determined.

The astronomical orientation was an essential factor in the layout of this city, but it remains to be studied if there is any correspondence with the constellations and other stars. What is certain is that Peralta points to certain very representative geographic elements of the Bajío, among them, the Cerro Culiacán.

This elevation of 2,834 meters is one of the most important in Guanajuato and is located to the south of the municipality of Cortazar. Cerro Culiacán can be observed from different points such as Victoria, Salvatierra, Celaya, and Abasolo (municipality where Peralta is located) and has always been a reference point as evidenced by its mention in historical documents.

Peralta is one of the archaeological sites of greater size and constructive diversity among the 174 that form the Bajío Tradition, characterized by the "sunken patio" (closed plazas delimited by rooms).

Within the Bajío Tradition, another archaeological zone stands out: Cañada de la Virgen. In that place, the sunrise and sunset of the Sun, the Moon, and Venus have been documented. The ancient architects built Cañada de la Virgen (in the municipality of San Miguel de Allende, Guanajuato) in relation to the direction of the west and the summer and winter solstices. In the records made, both the Sun and the Moon pass through the pyramidal base, twice a year.

The Sun and the Moon represent the creative duality, and the entrance to the underworld of both stars through the pyramidal base of Complex A or House of the thirteen heavens occurs in March, in their respective sunsets, that is, in the twentieth (the pre-Hispanic calendar was divided into 18 months of 20 days) of tozoztontli, 'small watchman for the fecundating rains'.

This was panned by the ancient pre-Hispanic inhabitants to mark the time of the year when spring is announced. The second moment takes place in October when the Sun takes shelter in the temple, which is related to winter, the dry season, and death. This takes place on the occasions of tepeilhuitl or 'feast of the mountains' and quecholli or 'flamingo bird'.