Study: Oldest civilization in Americas used astronomy to orient buildings

By Fernando Gimeno

Lima, Nov 18 (EFE).- Caral, a civilization that flourished around 5,000 years ago in what is today north-central Peru and is regarded as the oldest known pre-Columbian society, has now been shown to have partly used astronomical observations to determine the location and orientation of its most important built structures.

Contemporaneous to the great civilizations of the ancient world such as Egypt, Mesopotamia and China, Caral developed in the Supe River valley, about 130 kilometers (80 miles) north of where Lima is now located.

According to an article that appeared in Latin American Antiquity, a journal published by the Cambridge University Press, astronomical awareness played a role in the positioning of the Caral society’s buildings, including large pyramidal structures that were often associated with sunken circular plazas.

Based on measurements taken of 55 structures at 10 sites – eight directly related to the Supe River, including the civilization’s main city, known as Caral, and two nearer to the seashore – the researchers discovered two main orientations: one toward the so-called major lunar standstill (when the moon’s range of declination reaches a maximum) and another toward sunrise in the summer solstice, which in the Southern Hemisphere occurs in December.

A third, weaker orientation was toward the rising of Sirius, the brightest star at night in the Southern Hemisphere.

“The probability tests show that the orientation patterns were intentional. In no way was it something random or haphazard,” archaeologist Jose Ricra, the main author of the study along with Aldemar Crispin, told Efe.

Two Spanish experts took part in the gathering and processing of the data: archaeoastronomer Cesar Gonzalez-Garcia of the Institute of Heritage Sciences (Incipit) and astrophysicist Juan Antonio Belmonte of the Canary Islands Institute of Astrophysics.

Because of that civilization’s astronomical observations, it is not by chance that during every summer solstice the first rays of the sun enter through the stairs of the Caral Archaeological Site’s central pyramid and traverse its main hall through its niches.

“It’s very likely that a person had been on top of the buildings as the main point of observation to monitor both sunrises and sunsets, in the case of the solstices,” Crispin told Efe.

But the best observation point for this phenomenon, according to Ricra, was in one of the circular sunken plazas, a position from which the person could be admired by the rest of the population “with perhaps a religious or magical purpose” that affirmed the power of Caral’s elite.

The summer solstice probably marked the start of the harvest period, since that time of year coincides with the only moment when rains in the Andes mountains cause the normally almost bone-dry Supe River to fill with water.

More difficult to decipher are the buildings oriented toward the major lunar standstill, since although the moon is closely linked to fishing, that position only occurs once every 18.6 years.

Ricra said one explanation is that these people’s systematic observation of the moon led them to determine its southernmost point.

That knowledge came from the astronomical observatory located near Caral city, a find that led the director of that archaeological site, Ruth Shady, to make a case in a 1997 publication for the celestial orientation of the buildings, an assessment uncorroborated by data until now.

“It was an underground observatory, with a covered area for the person who did this work at night,” Shady, who has headed up the research work since 1994 but has not set foot in Caral for two years due to death threats from land traffickers, recalled in remarks to Efe. EFE

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