What is a lunar standstill? Problems of accuracy and validity ‘in the Thom paradigm'

Abstract

North West European late Neolithic and Early Bronze Age (EBA) monumental alignments on the sun's solstices and the moon's standstills were first systematically studied by Thom (Thom 1971).

Later research, since labelled the Thom paradigm' (Ruggles 1999), has rejected Thom's eclipse prediction and calendrical theories for these ancient alignments, yet retained his definition of a lunar standstill as the ' geocentric extreme declination' of the moon (Heggie 1981a, Heggie 1981b, Hoskin 2001, Morrison 1980, North 1996, Ruggles 1999, Thom 1971). Thom suggested that prehistoric extrapolation devices' calculated this mid-transit property of the moon from observed horizon alignments, but subsequent research has found no evidence for such devices. While a mid-transit definition of a lunar standstill is an accurate specification of the phenomena, it is based upon the premises of modern heliocentric astronomy and is unlikely to provide valid interpretations of the monument builder's use of horizon ' astronomy'. This paper attempts to demonstrate that the current theories used to explain the late Neolithic/EBA function of lunar standstill alignments do not fit the horizon, and therefore megalithic user, properties of lunar standstills. It is argued that a recent model (Sims 2006b) is more consistent with the archaeology and 'astronomy' of horizon-aligned monuments, and with any ethnographic elaboration of the Thom paradigm.