Editing Alexander Thom (section)

===Archaeoastronomical speculations===
He suggested several were built as [[astronomical complex]]es to predict [[eclipse]]s via nineteen-year cycles. Thom went on to identify numerous solar and stellar alignments at stone circles, providing the foundations for the scientific discipline of [[archaeoastronomy]].

He further suggested the prehistoric peoples of Britain must have used a solar method of keeping calendar. Based on statistical [[histogram]]s of observed [[declination]]s at horizon marks with no convenient star at −22°, +8°, +9° and +22° (except possibly [[Spica]] at +9°) between 2100 and 1600&nbsp;BCE, he suggested a year based on sixteen months; four with twenty two days, eleven with twenty three days, and one with twenty four.

Thom's suggested megalithic solar year was divided by [[midsummer]], [[Winter solstice|midwinter]], and the two [[equinox]]es into four and then subdivided into eight by early versions of the modern Christian festivals of [[Whitsun]], [[Lammas]], [[Martinmas]], and [[Candlemas]] (see [[Scottish Quarter Days]]). He found little evidence for further subdivision into thirty two, but noted "We do not know how sophisticated prehistoric man's calendar was, but the interesting thing is that he obtained declinations very close to those we have obtained as ideal".

Thom explored these topics further in his later books
* ''Megalithic Sites in Britain'' ([[Oxford University Press|Oxford]], 1967)
* ''Megalithic Lunar Observatories'' ([[Oxford University Press|Oxford]], 1971)
* ''Megalithic Remains in Britain and Brittany'' ([[Oxford University Press|Oxford]], 1978)
The last was written with his son Archie, after they carried out a detailed survey of the [[Carnac stones]] from 1970 to 1974.<ref name="Thom1967">{{cite book |first=Alexander |last=Thom |year=1967 |title=Megalithic Sites in Britain |page=107 |publisher=Oxford University Press, print on demand |isbn=978-0-19-813148-9 |url=https://books.google.com/books?id=UviAAAAAMAAJ |via=Google Books}}</ref>

Thom's ideas met with resistance from the [[archaeological]] community but were welcomed amongst elements of 1960s [[counter-culture]]. Along with [[Gerald Hawkins]]' new interpretation of [[Stonehenge]] as an [[astronomical]] 'computer' (see [[Archaeoastronomy and Stonehenge]]), Thom's theories were adopted by numerous enthusiasts for 'the lost wisdom of the ancients' and became commonly associated with [[pseudoscience]].{{Citation needed|date=April 2011}}