Thirteen towers arrayed on a hill in coastal Peru make up the oldest solar observatory in the Americas
Credit: National Aerial Service, Peru
ADELAIDE: Ancient Peruvians constructed a giant Sun observatory 2,300 years ago, according to a new study - almost two millennia before the Incas, who are much better known for Sun worshipping.
The spectacular structure, made up of 13 towers along a ridge near Chankillo in the coastal Peruvian desert, could have been used as a kind of solar calendar, accurate to within a few days, experts said.
The towers, which have long puzzled scientists, are believed to have marked the annual rising and setting arcs of the Sun. Ceremonial artefacts have been found near structures to the east and west of these towers, which may have been observation locations.
Accounts of Sun worship by the Incas date back to the 16th century AD. These include descriptions of 'Sun pillars' in Cusco, Peru, which were used to guide crop sowing and mark the dates for seasonal rituals. But the first complex states in northern Peru were believed to have arisen with the Moche civilisation around 400 AD.
However, according to a study published today in the U.S. journal Science, the structures at Chankillo have now been radiocarbon dated to between 200 and 300 BC. This means they predate the Moche by over 600 years.
The towers are part of a four-kilometre-square complex of buildings and plazas, surrounded by three wide, concentric walls. It had previously been suggested the structure was a fort, a temple or even a setting for ceremonial battles, wrote authors Ivan Ghezzi of the Pontifical Catholic University in Lima, Peru and Clive Ruggles from the University of Leicester in England.
However, the pair contest the idea that it had a military purpose, due to its numerous gates and poor water supply. Instead, they argue that it may have been a ceremonial complex with a solar observatory.
The "various towers and gaps would have provided a means to track the progress of the Sun up and down the horizon to within an accuracy of two or three days," they wrote.
A solar calendar would have been very useful along the arid Peruvian coast, anthropologist Daniel Sandweiss told Science in a news article. To accurately plant crops, "people need to know the date with some precision," said Sandweiss, an expert on ancient climate change at the University of Maine in Orono U.S.
The 13 towers run along a north-south ridge line in the complex, which is sited 400 km north of Lima, the Peruvian Capital. The researchers describe buildings to the west and east of that ridge that they believe acted as observation points for the rising and setting Sun, respectively.
The researchers report that the flat topped, rectangular towers are relatively well preserved. They vary in height from two to six metres with the slope of the ridge, and are regularly spaced with gaps of around five metres between each tower.
The western observation point has an intriguing 40-metre-long windowless corridor along one side, with an opening at one end that directly faced the towers. Around the opening, excavations uncovered offerings of pottery and shells, and the corridor contained ceremonially displayed ceramic figurines of soldiers. A ruin in far worse condition on the eastern side of the ridge forms almost an exact mirror of the western observation point.
The accompanying "labyrinthine passageways" used for ritual processes, strengthen the case for Chankillo being a solar observatory commented archaeoastronomist Anthony Aveni of Colgate University in New York, U.S. "The paper is well argued and consistent with the later practice of the use of 'towers' to mark the solar horizon movement," Aveni told Cosmos Online.
"Sun worship and related cosmological beliefs at Chankillo could have helped to legitimise the authority of an elite class," wrote the authors, "just as they did within the Inca empire two millennia later."
More information:
Chankillo: A 2300-Year-Old Solar Observatory in Coastal Peru, Science
