A recent paper published in the journal Latin American Antiquity examined how structures in the ancient city of Caral in Peru were oriented based on astronomy. The city itself, long since abandoned, dates back to around 3000 BCE, and the society that lived there was the Supe Culture, named for the river on which the city was built. And while much of that city is oriented parallel to the river, as one would expect from a predominantly agricultural society, several of the large and clearly important pyramidal buildings have an orientation that aligns with the full Moon and the June solstice.

First author César González-García explains: It is noteworthy that these orientations can be related to the precipitation cycles on the Andean summits, with the consequent beneficial floodings of the river, and thus with the agricultural cycles. That time also coincided with the end of the fishing season, taking place over a wide area of the nearby coast.

Coauthor Juan Antonio Belmonte notes: The results of the research in the position and the orientation of the main buildings show that the presence of the River Supe is the main determining influence on the orientation of the buildings because although they are not sited directly at the river, they are systematically parallel to it in a curious phenomenon, convergent with what was occurring at the same time thousands of kilometers away in Valley of the Nile.

These monuments of the Supe valley culture from five thousand years ago are now the first, and therefore oldest, examples of pre-Colombian American interactions between the landscape and the sky. And that is your daily reminder to look up and observe how astronomy influences your life.

More Information

IAC press release

“The River and the Sky: Astronomy and Topography in Caral Society, America’s First Urban Centers,” A. César González-García et al., 2021 March 23, Latin American Antiquity