This was astonishing! The accuracy of measurement is simply incredible, given that the Megalithic Second of arc is the smallest unit of geometric division apart from the Megalithic Yard itself, but the facts speak for themselves. Highly competent astronomers built these Neolithic structures. We were at a loss to understand how they could have measured such fine differences in latitude – but it seemed that somehow they did.
Next we pulled back to take in the bigger picture. Given the science that we could now see underpins the entire site of these gigantic structures we needed to consider why the people creating them had constructed a slightly bent alignment and built them with openings to each henge along an avenue pointing approximately northwest to southeast.
The first thing that is obvious is that the site is remarkably flat with only a very gentle slope from north to south. There are no large hills in the vicinity and so the view to all sides of the henges is unobstructed. There are hills in the distance, especially to the east, but when the banks were fully in place these would have been obscured. All heavenly bodies seen from the centre of any of the henges would rise from and fall back to the top of the banks, and there are no reference points on the horizon as are found at many stone circles. This is because from inside the henges there are no natural horizons to be seen, except through the deliberately engineered openings.
The location of the Thornborough henges is unusual in a British upland context because there are no hills of note for a staggering 127. 9 km (79.5 miles) to the southeast; the first being the 77 m-high hill upon which Lincoln Cathedral now stands. Strangely, the angle of the central and southern henges, their openings and the avenue, all point like a gun sight in the direction of the Lincoln mound. We could not think of any other location in the British Isles that delivers up such a long stretch of almost flat land. This seemed unlikely to be coincidence.
But what function could this virtual sightline serve? The curvature of the Earth makes it impossible to see such a distance but is there something significant about the location of Lincoln Cathedral? We were well aware that churches were often built on the ancient ‘holy’ sites from prehistory. Indeed, the tallest megalithic standing stone in Britain, with a height of 8 m and a circumference of 5 m, stands next to an old church in the village of Rudston, close to where Alan lives. The church and its graveyard were built inside Neolithic earthworks.
The distance between the centre of the southern Thornborough henge and the highest point at Lincoln is 127.13 km, which does not convert to any apparently meaningful distance in megalithic units. It was obvious that these Neolithic people could never have measured such a distance across the ground, using ropes for example, because every rise and fall would completely distort the result – even if they found a way to measure across rivers they would end up with a meaningless figure. But it occurred to Chris that they could use astronomy very accurately to measure relative latitude – the distance between two points on the Earth’s surface in terms of the north to south divide.
Figure 8. Thornborough henges circa 3500 BC
Using Google Earth, Chris carefully measured from the centre of the middle Thornborough henge to a point on the same latitude as the Lincoln mound, following the longitude of the henge centre to establish the north–south distance. The result was almost beyond belief.
The two places are exactly 1 Megalithic Degree of latitude apart – which means that they mark out 1/366th of the polar circumference of the Earth.
Simply stunning! This level of information changes everything we thought we knew about Thornborough – and about the extent of Neolithic scientific ability.
Out of curiosity Chris next projected the line in the opposite direction from the central henge through the northern henge, but here it crosses large hills and mountains. Nevertheless he continued the line across the Scottish mountains until it hit the Atlantic – very close to the Isle of Lewis.
Knowing that the beautifully preserved Megalithic stone circle of Callanish was on this northern island Chris measured the distance from the circle back down to Thornborough. The line from the Callanish circle to the centre of Thornborough is a rather meaningless 546,488 m, but when converted to Megalithic units it looks very interesting:
546,488 m = 658,689 MY
When divided by 366 × 360, to express the distance in Megalithic Degrees, the result is 5 Megalithic Degrees. A coincidence? We choose to make a decision based upon the evidence rather than on any preconceived ideas about intelligence or technical abilities of the inhabitants of the British Isles 5,500 years ago.
This prompted a question of whether or not the location of the Thornborough henges is geographically significant in any really fundamental way. A quick check revealed that these henges stand on a very significant latitude. To a very high degree of accuracy they are placed at a point that is 1/10th of the planet’s circumference from the North Pole!
A Special Location
The group behind these henges must have made measurements up and down the length of the British Isles – and maybe further – before they discovered that the area now called Thornborough is very special indeed. In addition to the henges and their flat sightlines we went on to discover yet more reasons why this location would have been meaningful for the architects concerned.
For the Neolithic peoples, Sirius, as the brightest star in the night sky, was almost certainly considered to be the chief object of the fixed heavens. It just so happens that Sirius was part of a very unusual relationship when viewed from the latitude of Thornborough. At the point in history that the Thornborough henges were built (circa 3500 BC), Sirius rose and set at the same point on the horizon as the Sun at the winter solstice (then 18 January) – this was almost exactly SE and SW. Such a happening must have created the impression that Sirius was linked in some way with the Sun when observed from Thornborough. At this location the Stone Age astronomers could witness the star apparently stopping the Sun’s progress across the horizon from north to south. (At midwinter when viewed from the northern hemisphere the Sun rises as far south as it ever does. The days are short, the weather cold and nature effectively dead. If the Sun cannot be prevented from travelling even further south then surely death and destruction must be the result.) From Thornborough it appeared that the great star Sirius halted the Sun’s southern progress and persuaded it to begin moving northwards again, towards summer and a time of plenty. To Stone Age farmers this must have seemed crucially important.
They would have realized that Sirius (like all stars) passed over their heads once per day and a total of 366 times per year. One can imagine that this would have prompted them to divide the circle of the day into 366 parts – which in another sense can be seen as 366 divisions (or degrees) of the sky. They could achieve this by creating a henge and dividing the circle of the banks into 366 parts. They would designate the divisions or degrees with thin poles pushed into the bank tops to mark out the width of one degree. With these in place the astronomer-priests could observe the movement of the stars across the horizon. To measure rising stars, such as Sirius, they would have made a frame – one-degree square as seen from the centre of the henge – and they would then have tilted it so that Sirius rose vertically in relation to the frame. In the case of Sirius this experiment was most probably done at the autumn equinox when Sirius was easiest to see.
Whilst we have been very critical of the general direction that archaeology has taken over recent years, there is no doubt that a tremendous amount of good work has been done at a technical level – and occasionally on an inspirational level as well. One archaeologist has made a rather guarded suggestion that the existence of the Thornborough henges may have had something to do with astronomy. Dr Jan Harding from Newcastle University has put forward the idea that the dogleg layout of the henges may be present because the builders wanted to construct the henges in a formation that copied the three stars we know as Orion’s Belt. And furthermore perhaps the nearby River Ouse was likened to the Milky Way.
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nbsp; When we first read this we thought it was a bit of a wild guess – possibly secretly inspired by Robert Bauval’s similar claim for the Giza pyramids. Whilst Bauval had a number of cultural as well as artefact-based reasons for his Orion claim in Egypt, there seemed to be nothing more than a similarity of shape at Thornborough. However, a check of the relative positions of the stars and the henges provided a near perfect fit (see figure 9).
Having found a raft of reasons to link these henges with the stars, we began to feel a great deal more sympathy with Harding’s suggestion and we started to investigate possible usage of the site in connection to Orion’s Belt and Sirius – to which this star group points.
The bank tops of the Thornborough henges formed an unchanging artificial horizon. When any planet or star appeared over a bank top it did so at exactly the same altitude as any other planet or star. This is not the normal state of affairs in an undulating landscape. (See figure 10.) As long as the bank tops are even, and also take account of the very slight slope upon which the henges were built, the scene is set for the most perfect form of naked-eye astronomical observatory possible.
One of the most important prerequisites for a successful series of experiments is to make sure that the circumstances under which they are carried out remain the same. This requirement was catered for perfectly by the giant henges of Thornborough and Dorchester-on-Thames. It is also clear that for experimental astronomy the use of stones, such as those to be found at Stonehenge and other circles, would be inefficient and totally inappropriate. Markers could be used at the super-henges and undoubtedly were, but these would have been wooden poles, dug into the soil just beyond the bank tops wherever they proved to be necessary. These could be ‘tweaked’ or removed altogether if necessary and placed somewhere completely different. It would have been relatively easy to move such poles around to wherever they were needed. Instructions from the centre of the henge, which was the ‘eyepiece’ of the naked-eye telescope, would allow helpers beyond the banks to do what was necessary to ensure that marker poles occupied ‘exactly’ the right spot.
Figure 9. Thornborough henges with Orion’s Belt superimposed
Stars will rise at different times across
an undulating horizon, making useful
experiments difficult or impossible.
Figure 10. Stars rising on an undulating horizon
Day after day, night after night, probably for centuries, specifically trained people would refine their knowledge of astronomy, maintain the ritual and agricultural calendars, and fix the date of special celebrations or events from their observations within the henges. So, what sort of observations could be undertaken utilizing the henges? The answer is – a multitude.
Observers within the henges could track the position of the rising Sun throughout the year, marking its northerly and southerly movement with the seasons. They could ‘fix’ the points of the Sun’s extreme positions in the midsummer and midwinter by use of marker poles. We know from lunar calendars carved onto antlers and bones from a very early period that humanity has always been fascinated by the strange and difficult-to-assess behaviour of the Moon. The Moon could have been studied for decades from the henges. Observers would eventually realize that its movements, in a monthly sense, mirror those of the Sun in its yearly behaviour. They would also pick up on more complicated lunar rhythms, such as the ‘Saros cycle’. The Saros cycle can be judged from lunar movement across a long period of time and is a combination of different types of lunar month that can be used to predict the occurrence of solar and lunar eclipses.
The observatories at Thornborough and at other henges could also be used to track the rising and setting points of both planets and stars. In the case of planets a better understanding of their sometimes tortuous movements would be gained, and absolute values for their periods could be established. Because planets are nearby objects that orbit the Sun, on more or less the same plane as the Earth, they appear to have highly complex movements. The stars are many light years, sometimes millions, further away than any planet and so they rise and set in the same place on the horizon for long periods of time – but not indefinitely.
There is a phenomenon all astronomers understand that is known as the precession of the equinoxes, and anyone using the giant henges as observatories across a long period of time could not have failed to notice its effect. Precession comes about as a result of secondary movements of the Earth. In addition to turning on its axis, and orbiting the Sun, the Earth has other, long-term movements. One of these is a tendency to behave somewhat like a child’s spinning top, which in addition to spinning, also ‘wobbles’ on its axis (see figure 11). One whole wobble takes a very long period of time in human terms (approximately 26,000 years). From the point of view of an earthbound observer the effect would be that, very gradually, stars would change their rising and setting points on the horizon. Even a couple of human generations would see stars altering their rising and setting points by a full degree, and so long-term observation would betray the existence of precession to the astronomer henge builders.
This last example offers a perfect explanation for the henges being so large. We would judge the gradual movement of a rising star on the horizon these days with advanced optical instruments. Telescopes make very small things look very big and, if they are fitted with crosshairs and measuring dials, they can be used to measure very small increments. The naked eye of a human being is far less sophisticated in terms of its ability to discriminate a small gap at a great distance. The best way to compensate for this inadequacy is to somehow ‘make’ the gap in question bigger. How can this be achieved? The answer is by looking out at the largest circle possible. In the case of naked-eye astronomy the true horizon is best, but it undulates and it is also sometimes difficult to see stars rising on the horizon because of atmospheric anomalies.
The Earth does not simply spin on its axis (A).
It also spins about its poles like a top (B).
Figure 11. Earth precession of the equinoxes
A very small henge might work reasonably well for some observational purposes but there would be a greater opportunity for error. If you wanted a really good scientifically accurate observatory you would want it to be very large, but not so big that you could not shout instructions from the centre. A perfect size would be the Thornborough trio. A series of straight poles driven into the earth just beyond the bank top would appear to be the finest of lines when seen from the centre of the henge. At night such a pole would not be seen at all, but what ‘would’ be seen would be the instant appearance of a star or planet that had just passed behind a first pole, which could then be timed until it appeared from behind a second pole placed 2 MY away in line with the star’s trajectory. Using a pendulum for timing the star produces split-second results.
Most archaeologists, and even some experts in the field of astroarchaeology, which is the study of ancient astronomy, would accept that there are great limitations to what could be expected of naked-eye astronomy. In a sense this is true because of the nature of human vision when compared with accurate telescopes. But we have already shown in our book Civilization One that there is another factor involved that is often either forgotten or not fully understood. This is an ability to measure the passage of time accurately, without which any form of astronomy is bound to be extremely limited in its possibilities. The best telescope in the world would be virtually useless in an astronomical sense if it were not allied to an accurate clock.
The three super-henges at Thornborough did not stand alone in the Stone Age landscape of North Yorkshire. Other super-henges have been noted around them. Some of these have only been detected since the advent of aircraft because they have been so degraded by weathering and ploughing that they now represent little more than ‘parch marks’ in the landscape. There are in fact no less than six large henges altogether in this part of the world, and their presence in so small an area tends to add to the feeling that this area of Britain was considered in
some way very special by those who laboured to dig the ditches and throw up the banks.
Dr Jan Harding is in no doubt that a religious imperative underlies the astronomical possibilities of the henges. We can accept that this may be true in part, but it must not obscure the excellence of the science involved. The study of astronomy, which is a purely scientific endeavour, is considered to be a recent innovation. Human beings all over the globe have been looking at the heavens for countless generations, but only around the 18th century did some investigators begin to abandon the notion of heavenly movements being associated with religion and fate. Before that time, and even today, for millions of people around the world, the patterns of stars to be seen in the sky and the complicated interplay formed by the Sun, Moon and the planets could be viewed as portents of future events. This is the study of astrology, and though modern astronomers get extremely agitated when the word astrology is mentioned, it is interesting to note that one of their greatest heroes, Sir Isaac Newton, spent far more of his life studying astrology than he did astronomy or physics.
To our ancient ancestors the sky, and especially the night sky, must have been a thing of wonder and, as we will discuss later, dread. Its significance is lost to us these days for a number of reasons but the greatest amongst these is light pollution. Most people in industrialized nations now live in an urban setting, surrounded by artificial lights of all kinds. This makes viewing the stars much more difficult. If any readers want to gain some appreciation of the way our ancient ancestors saw the night sky they will need to take themselves to some very isolated spot on a clear, crisp night, preferably when there is no Moon. The broad sweep of the Milky Way across the heavens, the panoply of stars and the apparent patterns created by the brightest and most magnificent of them all, form an awe-inspiring sight, even to those of us brought up to understand what planets and stars actually are. However, one star is brighter than all the others. This star is Sirius and it appears to have been of the most crucial importance to our species, both astronomically and astrologically, since the dawn of human awareness.
Before the Pyramids: Cracking Archaeology's Greatest Mystery Page 7