Stonehenge eclipse theory falls out of favour

A once-influential theory that Stonehenge functioned as an ancient astronomical computer capable of predicting eclipses has been substantially undermined by later research.

The idea originated with Boston astronomy professor Gerald Hawkins, who set out his argument to the BBC's Chronicle programme in August 1966, Fiona MAcdonald writes for the BBC.

He drew on the arrangement of the monument's stones, arches and holes together with calculations run on an early IBM computer.

Hawkins, who had visited Stonehenge in 1961 to study how its architecture framed the horizon, argued in his influential 1965 book Stonehenge Decoded that the site's 56 Aubrey holes formed a lunar counting system that could have been used to forecast eclipses.

Later calculations he carried out at the Harvard–Smithsonian Observatory appeared to show extensive alignments between the monument and the rising and setting positions of the Sun and Moon, leading him to conclude that Stonehenge had served as both a religious site and an astronomical observatory.

The theory held sway for decades, though archaeologists raised objections almost from the outset, including doubts over whether some of the 56 holes central to Hawkins' calculations were even man-made.

Modern research has since moved the picture on considerably. Professor Michael Parker Pearson, of University College London's Institute of Archaeology, says Hawkins' computer-based reading of the site is no longer accepted, with current evidence pointing to Stonehenge having been built in stages over more than 1,500 years rather than as a single coordinated project.

Parker Pearson adds that the monument's solar and lunar alignments were not precise enough for it to have worked as a measuring instrument – and that firm evidence of eclipse tracking in Britain dates to around 1000BC, some 1,500 to 2,000 years after Stonehenge's construction.