Observational Archaeoastronomy at Stonehenge: Winter and Summer Solstice Sun Rise and Set Alignments Accurate to 0.2 o in 4000 BP
Gordon R. Freeman and Phyllis J. Freeman
A COLLECTION OF PAPERS PRESENTED AT: THE 33RD ANNUAL MEETING OF THE CANADIAN ARCHAEOLOGICAL ASSOCIATION,The Ontario Archaeological Society Inc. (2001)
For several centuries it has been assumed that observations of Solstitial Sun Rises and Sets, if they were made at Stonehenge, were made from inside the Sarsen Circle looking outward. The outlying Heel Stone is in approximately the Summer Solstice Sun Rise direction when viewed from the centre of the Sarsen Circle. The fact that the Solstitial Sun rises Northerly of this line, and 4000 years ago rose still more Northerly of it, has been excused by the assumption that the observations were ceremonial, and the inaccuracy of 2° did not matter. Our long-term experience at a site in Alberta has shown that Sun lines were accurate to 0.1° to 0.2°, so we wondered whether the Stonehenge people in Britain had been as fussy. They had been.
During three study visits to Stonehenge, in the Decembers of 1995 and 1997, and June 1999, we discovered that accurate lines in 4000 BP were obtained by standing far outside the Sarsen Circle, and looking through narrow gaps between the Circle and Trilithon Stones, to the Sun Rise or Set on the horizon beyond. The Heel Stone was not a foresight for the Summer Solstice Sun Rise, but was an observation position for the Winter Solstice Sun Set into the side of a burial mound 1 km away, on the far side of the Sarsen Circle. The Rise and Set lines crossed over the middle of the Altar Stone, which 4000 years ago was lying flat in essentially the same position as now. The Winter Solstice alignments are reported in the present paper.