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Archeologists say they've identified what is by far the oldest astronomical observatory in the Americas. A series of towers near a temple in coastal Peru was built in the fourth century B.C. Those towers turn out to mark the sun's progress across the sky, according to a study in the latest Science magazine. It seems the sun played an important role in religious and political life long before the Incas' sun cult appeared.
NPR's Richard Harris reports.
RICHARD HARRIS: Nineteenth century explorers came across a curious scene in coastal Peru. An ancient fortress stood near a long ridge dotted with 13 stubby towers, kind of like a sea serpent's back. The early explorers suggested that the towers had something to do with the movement of the moon, and left it at that. A few years ago, Ivan Ghezzi at long last drummed up enough funding to excavate the site, which is called Chankillo, to uncover its secrets.
IVAN GHEZZI: Number one on my list was this possible relationship to astronomy.
HARRIS: Ghezzi is at the Catholic University of Peru and the national director of archeology. He quickly came to realize that the towers had nothing to do with the moon, but everything to do with the sun, when viewed from either of two structures that stood nearby.
GHEZZI: We could actually watch the sun rise aligned with the northernmost tower during the June solstice, and with the opposite tower at the other end of the line, you could see the sun rise at the December solstice. So we realized that here we had an astronomical device that was designed to keep track of the movement of the sun and therefore keep track of time.
HARRIS: And it's by far the earliest example of an observatory in the Americas. Ghezzi knows frustratingly little about the people who built the towers and the fortifications at Chankillo. For example, there is no telling whether they were in any way forerunners of the Incas, famous sun worshippers who appeared on the scene many centuries after this structure was built.
GHEZZI: We know that the Incas made powerful political statements based on the relationship between the sun and the king. And the Inca claimed to be the offspring of the sun. But now we have a society that is 1,800 years before the Inca and that clearly is using the sun as a way to make a political, social and ecological statement.
HARRIS: The towers weren't just a fancy sundial. For one thing, the fortifications nearby appear to protect a temple. Anthony Aveni is an archeo-astronomer at Colgate University. He agrees with Ghezzi's interpretation that the site is of great cultural and political significance, in addition to its practical use for timing, plantings, and harvests.
ANTHONY AVENI: So you have not just agricultural practicalities, the practical idea of keeping a calendar for agriculture, but embedded - that is all embedded within this religious ritual that they conducted. And then of course associated with religious ritual is hierarchical powers.
HARRIS: The priests who controlled the temple presumably held sway over the people around them and used their knowledge of astronomy as part of their mystique. The question as always in situations like this is whether the towers were really built with the astronomy in mind, or if the layout turns out to be a happy coincidence. But Aveni, for one, is convinced that this observatory is the real deal.
AVENI: It does work, and it works in a way that makes sense given what we know about Andean calendars.
HARRIS: The towers help mark other solar events, and they help count out a 10-day week, which Andean people used. Ivan Ghezzi says tourists may soon be able to judge this for themselves. He's working hard to turn the well-preserved ruins of Chankillo into a major destination.
Richard Harris, NPR News.