Professor Richard Atkinson, excavator and restorer of Stonehenge in the 1950’s, has stated:
‘The position at least of the Heel Stone and the Station Stones, and indeed the latitude of Stonehenge itself, were astronomically determined’.
The latitude of Stonehenge is 51 ̊10’ 42”. It has been suggested that this location was chosen because it fell upon the best position to observe the midwinter and midsummer risings and setting of the sun, together with the rising and setting position of the moon at its major and minor standstills, these being the limit of its movements during the 18.6 year cycle of its travel. At this latitude the equinoctial risings and settings are virtually opposite to each other so a sight line may have backsights and foresights; for example the midwinter sunset in the south west is on the opposite horizon to the midsummer sunrise in the north east; and the southerly moonset is opposite the northerly moonrise; etc.
Stonehenge’s latitude is unusual in that only at this approximate location do the moonrise at major standstill and the midwinter sunset occur at right angles to one another. This also applies to the moonset at major standstill and midsummer sunrise. This only applies to a relatively narrow corridor extending to 30 miles north or south of the latitude of Stonehenge.
The latitude of Whitmoor Barrow is 51̊ 16’ 24.9”. This is just short of seven miles north of the latitude of Stonehenge, and therefore well within the corridor of interest. Once one ventures outside this corridor then the foresights and backsights do not align, and the right angle relationship between the equinoxes and the moon standstills is lost.
Given the facts it would seem reasonable to suppose that other ‘observatory’ sites might lie upon the same latitude. Certainly I have faith in my discovery of the possible midwinter sunset line (See CROOKSBURY LINE), reinforced by my finding of a previously unknown barrow precisely on this line. There is an error on this alignment of just over three degrees compared with the Stonehenge figures, which could be accounted for by the elevation of the Hog’s Back, which provides a very level and clearly visible horizon from Whitmoor Barrow. The theodolite observation which I carried out at midwinter sunset in the 1980’s satisfied me that I was observing down the alignment towards the destroyed Hog’s Back Barrow. It would be good to check this but in the intervening years the scrub birch has grown tall and strong and it is no longer possible.
There was a time when researching the above would have been a doddle but with my advancing years I find it increasingly difficult to get my head around this stuff. If I am in error I ask that I may be put right – politely I hope!
Much of this research is based upon the published works of Robin Heath to whom I am indebted.