A Politecnico study reveals one of the mysteries of Stonehenge

A new interpretation about the archaeological site function thanks to Archaeoastronomy

Stonehenge continues to attract the attention of scholars and researchers more than four millenia after its construction. Giulio Magli, professor at the Politecnico di Milano, and Juan Antonio Belmonte, professor at Instituto de Astrofísica de Canarias and Universidad de La Laguna in Tenerife, have published on Antiquity, authoritative journal of Archaeology, an innovative study which helps explain the monument original function: the theory that Stonehenge was used as a solar calendar is wrong. Its structure instead accounts for a symbolic interest of the builders to the solar cycle, most probably related to the connections between afterlife and winter solstice in Neolithic societies

Archaeoastronomy, which often uses satellite images to study the orientation of archaelogical sites, has a key role in this interpretation, since Stonehenge exhibits an astronomical alignment to the sun which refers both to the summer solstice sunrise and to the winter solstice sunset.

In the paper, Magli and Belmonte refute the theory that the monument was used as a giant calendrical device, based on 365 days per year divided in 12 months, with the addition of a leap year every four. This calendar is identical to the Alexandrian one, introduced more than two millennia later, at the end of the first century BC as a combination of the Julian calendar and the Egyptian civil calendar. The authors show that this theory is based on a series of forced interpretations of the astronomical connections of the monument, as well as on debatable numerology and on unsupported analogies.

First of all, Magli and Belmonte refer to astronomy: they show that the slow movement of the sun at the horizon in the days close to solstices makes it impossible to control the correct working of the alleged calendar, as the device (remember: composed by huge stones) should be able to distinguish positions as accurate as a few arc minutes, that is, less than 1/10 of one degree.

Second, numerology. Attributing meanings to “numbers” in a monument is always a risky procedure. For example, in this case, a “key number” of the alleged calendar, 12, is not recognizable anywhere.

Finally, cultural paragons. A first elaboration of the 365 plus 1 day calendar is documented in Egypt only two millennia later than Stonehenge (and entered in use further centuries later). Besides, a transfer and elaboration of notions with Egypt occurred around 2600 BC has no archaeological basis.