Near an oasis in the coastal desert of Peru lies one of the strangest structures in the Americas. The structure is a fort built at the top of a hill with a line of 13 towers constructed to its south.
The fort is odd from a military point of view because it would have been almost impossible to defend: it has numerous entrances and no source of water inside. Then there are the towers, which are several hundred metres from the hilltop fort, lie in a straight line and serve no discernible defensive role.
So in 2007, archaeologists put forward a new interpretation. They suggested the site may have been a place of worship and a solar observatory, like Stonehenge, rather than a fort.
Their main evidence was that the towers line up with the sunrise on important dates such as summer and winter solstice.
Today, Amelia Sparavigna at the Politecnico di Torino in Italy adds some evidence using a program developed for calculating the position of the sun in the sky to determine how much sunlight should fall on solar panels.
She uses the program to show that the first tower lines up with sunrise on 21 June and the last tower lines up with the sunrise on 21 December.
She also shows the shadows the towers throw are useful too. Since the site is tropical, the shadows point north for half the year and south for the other half. What’s more, when there are no shadows the sun is at its zenith.
She points out that this would have been important information for a farming community, which would need to know when to plant seasonal crops.
That’s a useful interpretation. (In fact, Sparavigna has been using this software to re-analyse the role of the Sun in a number of ancient solar observatories round the world.)
However, many questions remain, not least of which is why there are 13 towers? Suggestions, if you have any, in the comments section please.
Ref: arxiv.org/abs/1208.3580: The Solar Towers Of Chankillo
Chanquillo or Chankillo is an ancient monumental complex in the Peruvian coastal desert, found in the Casma-Sechin basin in the Ancash Department of Peru. The ruins include the hilltop Chankillo fort, the nearby Thirteen Towers solar observatory, and residential and gathering areas. The Thirteen Towers have been interpreted as an astronomical observatory built in the 4th century BC. The culture that produced Chankillo is called the Casma/Sechin culture or the Sechin Complex.
The site covers about four square kilometres (1.5 square miles) and has been interpreted as a fortified temple.
The Thirteen Towers solar observatory
The regularly-spaced thirteen towers of Chankillo were constructed atop the ridge of a low hill running near north to south, forming a "toothed" horizon with narrow gaps at regular intervals. To the east and west investigators designated two possible observation points. From these vantages, the 300m long spread of the towers along the horizon corresponds very closely to the rising and setting positions of the sun over the year, albeit they are not all visible. On the winter solstice, the sun would rise behind the leftmost tower of Chankillo and rise behind each of the towers until it reached the rightmost tower six months later on the summer solstice, marking the passage of time. The Thirteen Towers of Chankillo could be the earliest known observatory in the Americas. Inhabitants of Chankillo would have been able to determine an accurate date, with an error of a day or two, by observing the sunrise or sunset from the correct tower.
The towers had been known to travelers for centuries, the astronomical function of the towers were speculated famously by Thor Heyerdahl in his book Kon-Tiki of the 1940s but only recently hypothesized at length in 2007 by Iván Ghezzi and Clive Ruggles.
Archaeological sites in Peru
- ^Peru 1:100 000, La Caleta Culebras (20-g). IGN (Instituto Geográfico Nacional - Perú).
- ^Jenkins, Dilwyn (2003). The Rough Guide to Peru. Rough Guides. p. 295. ISBN 9781843530749.
- ^ abPozorski, Shelia; Pozorski, Thomas; Pozorski, Thomas George (2006). Early Settlement and Subsistence in the Casma Valley, Peru. University of Iowa Press. p. 95. ISBN 9781587294624.
- ^Gerster, Georg (2005). The Past from Above: Aerial Photographs of Archaeological Sites. Getty Publications. p. 197. ISBN 9780892368754.
- ^"SITIO ARQUEOLOGICO CHANQUILLO" (in Spanish). MINCETUR. Retrieved 2017-06-01.
- ^ abGhezzi, Ivan; Ruggles, Clive (2007). "Chankillo: A 2300-Year-Old Solar Observatory in Coastal Peru". Science. 315 (5816): 1239–1243. Bibcode:2007Sci...315.1239G. doi:10.1126/science.1136415. ISSN 0036-8075. PMID 17332405.
- ^ abGhezzi, Ivan (2006). "Religious Warfare at Chankillo". In Isbell, William H.; Silverman, Helaine. Andean Archaeology III. Springer US. pp. 67–84. doi:10.1007/0-387-28940-2_4. ISBN 9780387289397.
- ^DK (2010-06-21). Space: A Visual Encyclopedia. Penguin. p. 209. ISBN 9780756666286.
- ^ abBBC/Open University documentary, Broadcast March 2011, Downloadable demonstration of Towers at sunrise.
- ^Atwood, Roger. " "Solar Observatory at Chankillo, Peru." Archaeology. Volume 61 Number 1, January/February 2008. http://www.archaeology.org/0801/topten/solar_observatory.html.