|A short background description of archeoastronomy, also called astro-archaeology.|
The investigation of the astronomical potential of prehistoric megalithic sites is not a field which has particular appeal to modern archaeologists in Scotland or England. The main reason for this is possibly that the subject requires some skills and interests which are outside those generally possessed by the archaeological community. Another reason is that archaeology has never developed the prestige and authority of other professions. Consequently lay people and interested outsiders from other fields feel free to offer their ideas and opinions about archaeological subjects to professional archaeologists in a way that they would never do about conveyancing to a lawyer or about caries to a dentist. Archaeologists can find this annoying.
As the investigations have gone on over the last hundred years into the relationships between megalithic sites and the sun and the moon, the work has mainly been done by professionals from other disciplines, such as engineers, artists, astronomers and surveyors, as a sideline in their working lives or as a hobby. Such people sometimes have a shaky understanding of what is actually known about prehistoric societies, and are not disposed to read the literature to improve it, before launching into print with their own theories. This ignorance, combined with the monomania about one aspect of prehistoric culture which some astronomical investigators suffer from, has caused many archaeologists to be dismissive of and hostile to the whole subject.
This is especially true when archaeo-astronomers postulate a class of stone-age scientists who erected the stones and then spent their brief lives studying the minor perturbation of the moon.
A reader should be aware of this hostility, as it is the reason many archaeological guidebooks ignore archaeastronomy completely. This is unfortunate, as it would be more reasonable, considering the acceptance of the orientations of such imposing sites as Stonehenge and Newgrange, to allow that archaeoastronomy has some validity, and contend about the level and sophistication of prehistoric observations, rather than their actual existence. However, a visitor to many of the sites which are in state care and have information boards provided will notice that there is usually no information about possible astronomical purpose given.
Studies on the astronomical orientations built into prehistoric monuments have gone on for over a century in Scotland. Early workers in the field tended to examine all monuments in their local area and attempt to integrate them into a grand scheme. An example of this from the 19th century is the work of the school teacher Magnus Spence on Orkney. He interpreted the chambered cairn of Maeshowe, and the rings at Stenness and Brodgar and other nearby single stones as inter-related in a series of alignments which covered the solstices, the equinoxes, and other calendar dates [Spence 1894]. Such schemes usually ignore the chronological sequence of the individual sites, which may not even be contemporary.
Sir Norman Lockyer, an astronomer and physicist, and founder and editor of the journal 'Nature', developed a scientific approach to the investigation of prehistoric astronomy, and launched the modern interest in the subject. His surveys of the orientation of Greek and Egyptian temples, and his studies of Stonehenge and other monuments were widely published and widely read in the late 19th and early years of the 20th century.
He concluded that early British megalithic sites were mostly orientated to the rising or setting sun at the quarter days, in November, February, May and August, or to stars which rose before the sun at those times of year. He believed that customs changed over the centuries, and later megalithic sites were orientated mainly towards the solstices.
One of those who was stimulated by Lockyer's books to begin his own work was the Irishman H. Boyle Somerville, a naval captain who spent much time surveying the coastlines of Scotland and Ireland. He had the resources and the expertise to also survey megalithic sites in those areas, and believed that Lockyer's thesis was well confirmed by his own work. In addition, he suggested that many megalithic alignments were towards the extreme rising and setting positions of the moon, and was the first to produce accurate scale plans of many important sites. His writings have the benefit of clarity, and his explanation of what 'direction' actually means, which occurs in his paper on the orientations incorporated into the monument at Callanish, is worth repeating :
'For what is Orientation, or Direction ? What is the meaning of North, South, East, or West ? How did we derive these fixed points to start with ?
Not from any local or national origin ; for pure Direction is entirely independent of locality ; it is, in fact, derived solely from the movements of the "heavens". It is only by reference to the position of the stars, sun, or moon, that Azimuth, or true Direction, exists : there is no other meaning in the term.
So that when [at Callanish] we find two lines of megaliths laid out on absolute "cardinal points", viz., West and South, the setting and nooning points respectively, we realize that it can only have been accomplished by some reference to the heavenly bodies....' [Boyle Somerville 1912, page 36]
Alexander Thom, a Scotsman and professor of engineering at Oxford was the man who revived interest in megalithic astronomy in recent times. His work was based on surveys of hundreds of sites in Scotland, England, Wales and Brittany, and subsequent analysis of the results, which led him to believe that an eight, or even sixteen month solar calendar was in use in prehistoric times. He also confirmed the megalith builders' interest in the movements of the moon, and particularly in the extreme positions of the moon's 18.6 year cycle, the major and minor standstills.
Thom also believed that his accurate surveys of the stone circles had revealed that a common unit of measurement was in use in prehistoric times, which he named the 'megalthic yard' of 2.72 feet (or 0.83 metres) [Thom 1967, 1971]. His work implied a different picture of the nature and organisation of Neolithic and Early Bronze Age society to that which archaeologists generally saw. Euan Mackie, keeper of the Hunterian museum at Glasgow University, then attempted to redraw this image of the prehistoric past. Mackie believed that to achieve results such as Thom discovered there had to be a class of wise men or 'astronomer-priests' in prehistoric times who had great authority and directed the erection of the stones and built up an expertise in emprical astronomy [Mackie 1977]. This was in contrast to the common interpretation of Neolithic society as mainly consisting of dispersed, isolated and egalitarian farming groups.
The work of Thom and the ideas of Mackie have met a variable response from the archaeological community, and re-assessments of Thom's work involving large surveying programmes have been carried out [Ruggles 1984]. References to all these researches will occur on the site description pages. It is fortunate for Scotland that many of the most important, spectacular and controversial megalithic observing sites are in this country, and accessible to visitors.
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