Saturday, July 20, 2024

Major Lunar Standstill July 19th 2024

At Moonrise on the 19th July 2024, the Moon was very close (within a quarter of a degree) to its maximum southerly declination in its 18.61 regression of the lunar nodes cycle.

I'd booked to go in to Stonehenge on the late evening "Special Access" session, in order to try and improve on my photo from July 9th 2006 of the Moonrise in line with the northeastern side of the Station Stone rectangle.

July 9th 2006 Major Lunar Standstill - 18 years and 10 days ago

(In the mid-1960s, Peter Newham and Gerald Hawkins had independently suggested that the long sides of the Station Stone rectangle were aligned to the southernmost moonrise and northernmost moonset at the lunar standstill - see this article for the background to Newham's work.)

In the intervening 18+ years, English Heritage have placed a marker at the approximate position of where Station Stone 94 once stood (the Station Stone is no longer present, but its stonehole has been found through archaeology). There is a slight inaccuracy in its position (perhaps half a meter off), but it serves as a useful reference.

Moonrise was timed for 20:41 BST (19:41 UT) but the trees of Luxemborough Plantation on the SE horizon delay the Moon's appearance by around 5 minutes.

I set up my camera so that I was in line with the marker for SS94 and the (still present, though slumped) Station Stone 91 on the opposite side of the monument.

Initial photo on the alignment from SS94 marker to SS91.
Features of other visitors pixellated for privacy.

I knew I was further to the southwest of my 2006 position directly over SS94 (a spot which I'd then chosen by estimating the centre of the area inscribed by the bank of the North Barrow), so was expecting the Moon's position at appearance to be somewhat different to then, relative to the treeline.

With the camera taking a shot automatically every 15 seconds, I spent the next few minutes over the rope a couple of metres to the NE to try and spot the first gleam of the 97% waxing gibbous Moon over the treetops. Fortunately, there was no cloud cover at the horizon at all - which wasn't the case back in 2006.

And then, at 20:46:55, I spotted it peeping out of Luxemborough Plantation's trees. Rats! It was too far south (to the right) for my camera to have caught it - and would be blocked by the large sarsens of the NE side of the outer circle. I grabbed the tripod and quickly moved the camera to catch the Moonrise.

Off-alignment by about 2m to the NE with the Moon's upper limb just appearing.
The shot has been contrast enhanced to improve visibility.

OK, so this is somewhat annoying! First gleam over the true horizon would definitely have been visible from my original spot if there were no trees in the way. We really ought to cut a path through Luxemborough Plantation to restore this sightline.

Back home, I decided that it would a useful exercise to montage these two shots using the treeline as the reference to see what it would have looked like in an ideal world. The fractional parallax introduced by moving 2m NE off-alignment is tiny since the trees are a considerable distance away, so it's worth doing.

Here's the result.

Montage of original shot in the alignment position with the off-alignment photo,
using the treeline as the registration reference.

All very well, but how can I tell where the horizon (sans trees) would be? I can guess, but long experience of carrying out observations at Stonehenge has taught me that subtleties in both the shapes of the stones and the horizon profile are important and need to be considered.

Happily, due to the work of David Hoyle ( there is an excellent LIDAR/DTM terrain model for the Stonehenge landscape which can be loaded into Stellarium to give a pretty accurate representation of the actual horizon profile.

This is Stellarium's view of 20:46:55 BST on the 19th July 2024:

Stellarium view of Moonrise at the same instant as the first appearance of the Moon over the trees.
The Archaeolines plug-in is being used to show the arcs of the Major Standstill Moon.

A further montage, using the Moon size and the hill at 135° azimuth as reference points, allows me to see the whole picture.

Final montage with true horizon profile and rising arc of Major Lunar Standstill.
My yellow block for SS91 may be a tad short - it was a quick guess for visualisation.

At first glance, this looks excellent - the Major Lunar Standstill southernmost Moonrise appears as if it will emerge from the intersection point of the tip of Station Stone 91 and the true horizon. I suspect my yellow block is too short, but it was a rough positional indicator I plonked in while doing these montages. It's quite a long stone (3m or so) that's slumped right over and is resting on the earthwork bank.

Remember that the Moon on the 19th July 2024 is not precisely at its southernmost extreme declination, as is evidenced by the fact that Stellarium doesn't have it centred on the green rising arc lines.

However - there's one more factor we need to consider and that's the change in the Obliquity of the Ecliptic.

Earth's rotational axis is presently tilted over at roughly 23.5° to the plane of the Earth's orbit - which is why we have seasons (and indeed solstices that mark the turning points in the year). Back when Stonehenge was built, the tilt was 24°. This additional 0.5° tilt has an impact on the rising azimuths of the Sun and Moon at their extreme north and south limits.

In this specific case, 4,500 years ago when the large sarsens at Stonehenge were erected (or 5,000 years ago for the Station Stones - that's another story!) the Moon would have appeared to rise a further 1° to the right of where we are seeing it in these photos - that's two Moon diameters.

The implication of this is serious.

It means that the northeastern edge (long side) of the Station Stone rectangle is not precisely aligned with the southernmost possible Moonrise position - by something like 1.5° to 2° in azimuth based on these photos.

If we also factor in the potential inaccuracy of the position of the marker for SS94 it gets worse still - we may be looking at an error in alignment of up to 2.5° or 5 lunar diameters!

Newham and Hawkins' suggestion that the Station Stone rectangle's long sides are exactly pointed at the southernmost moonrise (SE) and northernmost moonset (NW) is starting to seem a little off.

We know, as modern astronomers, that the chances of catching the Moon rising or setting exactly at its extremest possible declination north or south of the celestial equator are very slight. The Moon races around its orbit (and hence our sky) really quickly so everything has to come together - orbitally and weatherly - for a precise observation of the extreme to be done. That may only be possible once in a generation.

What all this serves to show is that we need to devote proper resources to researching what is actually seen at Stonehenge during these occasions of rare potential astronomical alignments.

We need to be absolutely sure that if we're going to put modern markers in the ground, that they are accurately positioned which implies confirming earlier work about stonehole positions though new archaeological digs with modern DGPS instead of relying on 1950s surveys and interpretation.

And we need to seriously consider restoring sightlines in key directions by selectively felling some trees that obscure the true horizon. Luxemborough Plantation (SE), Larkhill (NE), Normanton Gorse (SW) and Fargo Wood (NW) will all need attention.

The questions that are raised here deserve further investigation. We have the chance over the next 12 months to refine my observations as we progress though this Major Lunar Standstill season (2025 is the key year).

Or not. In which case, we'll have to wait another 18.61 years for the next opportunity to do so.

Friday, July 05, 2024

Thoughts on Bluestone Trilithons

Within the collection of bluestones at Stonehenge are several interesting examples that show distinct signs of having been part of independent, tooled, structures.

Stone 36 and Stone 150 are clearly lintels having mortise holes worked into one of each of their faces, in much the same way that the lintels of the outer sarsen circle and inner horseshoe of sarsen trilithons do.

Stone 150 is quite rounded, and lies prone in the turf in the NE quadrant of the bluestone circle but Stone 36 is far more elegant and is almost entirely buried in the southern quadrant - in fact 36 is arguably the finest dressed stone on the site.

Stone 150

Stone 36

Stone 36, having been lifted for inspection during the excavations of 1954

Stonehenge plan showing the positions of Stones 36 and 150
© Anthony Johnson, annotations by Simon Banton

As Julian Richards writes, in "Stonehenge - The Story So Far (2nd ed.)", referring to Atkinson's lifting of Stone 36 in 1954:

Apart from its sheer aesthetic qualities, Stone 36 posed some interesting questions. Along with stone 150 it was the second bluestone lintel to be identified and there were the uprights to go with them, pillars in the bluestone horseshoe that showed signs of having originally had tenons. So Atkinson could suggest a phase of ‘tooled bluestones’ which must, as there were now two lintels, have included at least two miniature trilithons. These, on the evidence of the mortice holes in the lintels would have looked very different from the much larger sarsen examples. The lintels would have extended beyond the edges of the slender pillars on which they perched, the space between the pillars and the height of the lintel sufficient to allow people to pass through.  The remarkable Stone 36 also provided evidence that this was not a short-lived structure. One of its mortice holes was surrounded by a shallow depression, presumably a carefully worked seating for the upright on which it sat, and within this hollow the surface of the stone appeared worn, even polished. This did not appear to be deliberate but more the result of friction, perhaps caused by the expansion and contraction of the touching stones. But such a polish would only develop very slowly, suggesting that these stones must have stood as trilithons for many years.

Could these two bluestone miniature trilithons have been the archetypes that eventually gave rise to much larger echoes of similar design in the enormous sarsen trilithons?

If so, then what could have been the intent behind the original creation of the bluestone versions? And where were they erected? Clearly not close to the current positions of 36 and 150 since they are remote from their supposed companion uprights which are components of the inner bluestone horseshoe arrangement and which carry the battered down remnants of tenons on their upper surfaces.

These are all repurposed stones - the bluestones have been rearranged a number of times in prehistory - and 150 in particular has been used, finally, as a pillar of the bluestone circle which was oriented so that its mortise holes would not be visible from the interior of the monument.

Bluestones have a remarkable capacity for being used as lithophones - "rock gongs" if you like. When found at their outcrops in the Preseli Hills in South West Wales, experimentally striking them with a rubber mallet or a deer antler will soon discover that certain ones that will "ring" like a bell.

They have to be positioned just right - balanced without being buried in the ground so that they can resonate when struck. The following video shows my attempts at getting a note out of a number of examples in 2023.

If there were two bluestone trilithons at some point in Stonehenge (transported there having been dismantled from an earlier monument in Preseli, perhaps), could the design have been in an effort to support two appropriate stones above the ground so that they could be easily "rung"?

What are the implications of such a suggestion? Is there an acoustic aspect to the use of Stonehenge that has been hinted at by a number of other researchers? One which employed the bluestones?

Are the bluestone trilithons in fact engineered sound sources? Maybe the "voices" of the stones were thought to have been in some way special in their own right, and bringing them to sing at the site of the future Stonehenge was important for an unknowable (to us) reason.

Given that the final arrangement of the bluestones at Stonehenge has them all either fallen, half-buried, or deeply embedded in the chalk (in the case of the upright ones) it seems that if they did have an original acoustic purpose then this was subsequently either forgotten or discounted by the people who incorporated them into the much later monument - even if they did echo their form in the horseshoe of enormous sarsen trilithons.

Sunday, May 12, 2024

Stone 11 Shadow Effect

Stone 11 is the mysteriously half-height, half-width upright in the southern quadrant of the outer sarsen circle at Stonehenge.

Plan of Stonehenge indicating position of Stone 11
Plan of Stonehenge indicating position of Stone 11

Stone 11 seen from the south
Stone 11 seen from the south

Several suggestions have been made to explain its curious dimensions - that the builders ran out of bigger stones, that it's a reused lintel, that it marks a division of the 30 uprights into three groups of 10 (the other marker being Stone 21) for calendrical reasons...

The 2012 Antiquity paper "Stonehenge Remodelled" (Darvill, T. et al. (2012) ‘Stonehenge remodelled’, Antiquity, 86(334), pp. 1021–1040. doi:10.1017/S0003598X00048225) offers:

...stone 11 (south) is narrower and shorter than the others perhaps to somehow mark the southern entrance (or it may even have been a later replacement).

None of those explanations have ever felt entirely satisfactory to me.

Recently I was watching Dr. Terence Meaden's video presentation to the 2024 Megalithomania Conference, on the topic of Pytheas the Greek's voyage to Britain and Thule.

Terence is always interesting and has had enlightening things to say about megalithic structures for decades. It was he that pointed out, for instance, that the Heelstone casts a shadow that penetrates into the centre of Stonehenge on the Summer Solstice (see "The Shadow of the Heelstone" on this site for more info).

While he was explaining his hypothesis that Stone 11 is of reduced height to represent "half" in the count of sarsens in the outer circle - ie that the circle conceptually held 29.5 stones rather than 30, and so could be used as a lunar calendar count, twelve times round it making 354 days then continuing the count on to Stone 11 would bring the day tally up to 365 and hence one solar year - he put up this diagram from his 2017 paper "Stonehenge and Avebury: Megalithic shadow casting at the solstices at sunrise":

Fig. 7 from "Stonehenge and Avebury: Megalithic shadow casting at the solstices at sunrise"
Journal of Lithic Studies (2017) vol. 4, nr. 4, p. 39-66 doi:10.2218/jls.v4i4.1920

Terence points out that the shadow of Stone 11 falls on Stone 40 at Winter Solstice Sunrise, and suggests that the male Stone 11 deliberately interacts with the female Stone 40 in this way.

Those familiar with his work will recognise this as a common theme in his research - phallic upright stones casting shadows onto recumbent receiving stones at key times in the year.

The next image in his presentation gave me goosebumps.

Stone 11 just after sunrise near Winter Solstice with the Sun at its rising azimuth of 2500 BCE
Stone 11 just after sunrise near Winter Solstice with the Sun at its rising azimuth of 2500 BCE

The shadow of Stone 11 can clearly be seen clipping the fallen Stone 14's right hand end (its upper end when erect), and Stone 40 (a bluestone) is directly behind this fallen sarsen lying prone in the turf - not visible in this shot, exactly under Stone 11's shadow. But that's not what grabbed me.

The shadow of Stone 11 continues across the ground and directly intersects with Station Stone 93! This contrast-enhanced closeup of Terence's image shows it well.

Stone 11's shadow hitting Station Stone 93
Stone 11's shadow hitting Station Stone 93

For this to happen, Stone 11 has to be a very particular height and width - any wider and its shadow will not match the width of Station Stone 93, any taller and the shadow will extend well beyond 93's peak.

We have to remember to account for the shift in the Earth's axial tilt from 24° to 23.5° since 2500 BCE. 

At winter solstice 2500 BCE, the Sun reached "full orb" over Coneybury Hill at an azimuth of 130° 20':

Full orb winter solstice Sun position, 2500 BCE, from Stellarium
Full orb winter solstice Sun position, 2500 BCE

In our era, on the 27th December 2014 (when Terence's photo was taken), the Sun is at a higher altitude when it reaches this azimuth:

Sun's position on 27th December 2014 when it reaches azimuth 130° 20'
Sun's position on 27th December 2014 when it reaches azimuth 130° 20'

Its altitude in our era is 1° 6', back in 2500 BCE it was 0° 26' - a difference of 40' of arc. This difference puts the tip of Stone 11's shadow fractionally lower on Stone 93 now than it would have been then.

It seems likely that Station Stone 93 would have been completely and exactly engulfed by the shadow of Stone 11 cast by the full orb risen Sun at winter solstice in 2500 BCE.

Drawing this shadow line on the reference plan of Stonehenge from "Stonehenge in its Landscape" (Cleal et al, 1995), along with the secondary solstice axis identified originally by Gordon Freeman (see "The Secondary Solstice Axis" on this site) highlights their parallel nature.

Stone 11 shadow (black line) and the secondary solstice alignment (red line)
Stone 11 shadow (black line) and the secondary solstice alignment (red line)

Zooming in on this, and incorporating the plan of the parchmarks for the missing stones 17, 18, 19 and 20 from "Parchmarks at Stonehenge, July 2013" (Banton, S., Bowden, M., Daw, T., Grady, D., & Soutar, S. (2014) Antiquity, 88(341), 733-739 reveals an elegant aspect to this shadow line.

Closeup incorporating the plan of the parchmarks identifying the positions of Stones 17, 18, 19 and 20
Closeup incorporating the plan of the parchmarks identifying the positions of Stones 17, 18, 19 and 20

... the shadow of Stone 11 (the black line) passes exactly through the gap where missing stone 18 and 19 would have stood (if indeed, they'd ever been erected - the jury's out on that one) - so it would not have been blocked by them.

In the end what does this mean?

It appears possible that Stone 11 was positioned and shaped to create a shadowplay effect at winter solstice when Stonehenge was built, one that targeted Station Stone 93 very precisely both in position and size.

If Stone 11 was fatter and taller, this wouldn't have worked so neatly.

All that remains to be explained is the leaning nature of Stone 11, because it is not perfectly upright.

Stone 11 leaning towards the south
Stone 11 leaning towards the south

... how does this affect things? Is it intentional? I'm looking at this picture and noticing that the right hand edge of the stone is almost perfectly vertical, compensating for the lean.

The investigation into that is a story for another day.

Many thanks to Terence for giving me permission to use his images.

Monday, May 09, 2022

The Secondary Solstice Axis

Everyone knows about the primary Stonehenge solstice axis - it runs from Summer Solstice Sunrise to Winter Solstice Sunset.

Every June 21st (or thereabouts - it varies depending on leap years and other things), thousands of people turn up and spend the night in and around the monument waiting for the Sun to rise out of the Heelstone.

And every December 21st (or thereabouts), hardly anyone bothers to show up specifically to stand by the Heelstone to watch the Sun set into the centre of the monument just to the left of Stone 56 in what would have been the gap between the two uprights of the tallest trilithon had it not collapsed in antiquity.

But there's a second solstice axis, which runs from Winter Solstice Sunrise to Summer Solstice Sunset.

I first became aware of this as a result of reading Prof. Gordon Freeman's book "Canada's Stonehenge" back in 2009. In it, Gordon discusses the alignments of a First Nation's medicine wheel in Alberta and also those of Stonehenge. Gordon came to the UK to carry out observations over a number of years from the 1990s onwards, making him somewhat unusual in archaeoastronomy terms in that he actually used his own eyes on site to arrive at his conclusions instead of relying only on plans, maps and computer simulations.

In the book (2nd edition is called "Hidden Stonehenge") he pointed out that there's a direct sightline that runs through the monument on a roughly NW-SE axis which points directly at the rising point of the Sun over Coneybury Hill at Winter Solstice, and at the setting point of the Sun into Fargo Wood at Summer Solstice in the opposite direction.

Gordon had never been lucky enough to make a direct observation of the Winter Solstice Sunrise on the actual solstice due to adverse weather every time he'd visited. To combat this, he'd projected the Sun's solstice rising position based on photos he'd taken of near-Solstice risings that he had been able to observe.

Intrigued by this, I resolved to try and make some observations of my own.

The alignment towards Winter Solstice Sunrise that Gordon suggested runs on the dotted line shown in the following oblique aerial view...

Aerial view of the secondary axis alignment

... starting from the visitor path NW of the monument, it goes via the midpoint between Stones 22 and 21 of the outer circle, then through a notch about 1.5m above the ground in the SW edge of Stone 58 of the western trilithon, skirts the NE edge of Bluestone 69 then the NE edge of Stone 53 of the SE trilithon and passes over the (now-fallen) stump of Stone 8. When S8 was originally standing, the line would have skirted its SW edge.

The view along this sightline from the visitor path is like this, with the relevant stones numbered and the notch indicated:

View along the sightline from the visitor path

The closeup view (to show the Coneybury Hill horizon) is like this:

Closeup view showing Coneybury Hill horizon

Note the very handily placed electricity pylon on the horizon for reference.

In 2011, a couple of weeks before Winter Solstice, I was able to get some photos of the rising Sun over Coneybury Hill standing on the alignment on the SE side of Stonehenge (to get an unobstructed view), which I montaged together with a wider view taken through the notch - both sets using the pylon as the reference mark.

Knowing the declination of the Sun on the 10th December, the apparent width of the solar disc and the declination the Sun would have had in 2500BC I was able to create the next image to indicate the rising position of the Sun on Winter Solstice in our era and also what it would have been when Stonehenge was built. Montage of sunrise photos and alignment reference image

As luck would have it, on the 22nd December 2011 there was a hazy sunrise that allowed me to have some confidence my projection so far was about right.

Hazy 22nd December 2011 Sunrise

So far so good - but what I really needed to confirm my projection was correct for our era was to get a properly clear photo of the actual Winter Solstice Sunrise - the same problem Gordon had had, and never managed to achieve.

A year later, in 2012, at the Winter Solstice "Managed Open Access" event the crowd of attendees was blessed by a perfectly clear sky right to the horizon over Coneybury Hill and I was able to get the reference photo I needed (again, taken SE of the monument exactly on the alignment for an unobstructed view).

Knowing the exact azimuth of the Sun at the instant the photo was taken, and being able to calculate the azimuth that the rising Winter Solstice Sun would have had in 2500BC (when the angle of the Earth's axial tilt was 24° rather than 23.5°) I was now able to construct the equivalent view back when Stonehenge was built...

Full Orb over Coneybury Hill in 2012, and the projected position in 2500BC

...and this (via the handy electricity pylon) then allowed me to create an updated montage of the view seen along the alignment via the notch itself, both now and in 2500BC.Composite view of Winter Solstice Sunrise via the Stone 58 notch, with an inset showing what would be seen in 2500BCThe alignment first identified by Prof. Gordon Freeman is targeted like a rifle sight at the precise position of Full Orb of the Winter Solstice Sunrise over Coneybury Hill when Stonehenge was built.

I'd been corresponding with Gordon since I'd first read his book, and sent him my results.


There's another wrinkle.

Hidden from view in that oblique aerial photo which shows the path of the alignment through the monument is another stone. A very important stone. A unique stone. In a very specific position.

It's this one. 

Not the obvious ones you can see dominating the picture - they're the collapsed parts of the tallest trilithon - I mean the one you can barely make out at the ground level, buried in the grass that starts in the lower left corner then disappears under Stone 55b before reappearing between 55b and 156 in the middle-right of the image. There are some more photos of it on my other site The Stones of Stonehenge.

The two visible parts of it are indicated by red ellipses and the red lines show how it lies below ground. The dotted lines show that it continues under the fallen lintel Stone 156 and a further piece of it is visible at ground level just beyond (though not in this particular photo).

This is Stone 80 - aka the Altar Stone. It's a roughly 5m long by 1m wide by 0.5m thick slab of micaceous Devonian sandstone that isn't local to Wiltshire (unlike the sarsens). It's not local to the Preseli Mountains (unlike the bluestones) either. Our current best guess is that it may be from the Senni Formation of east Wales around the Brecon Beacons (although further work is ongoing to try and place its origin more securely).

Here's a drawing showing its position in the monument. The photo above is taken roughly from where the + is, looking towards the bottom left of the diagram.
Diagram of location of Altar Stone

There has long been an argument about the Altar Stone - was it always on the ground, or was it knocked flat when the tallest trilithon's SE upright and its lintel fell?

I believe we can answer that question once and for all, based on Gordon's alignment. The alignment he noticed, and which I've described in detail above, runs directly along the centreline of the long axis of the Altar Stone.
Diagram of location of Altar Stone with alignment shown

Not only that, but most reconstructions and plans of Stonehenge show the Altar Stone at 90° to the primary solstice axis (the one that runs from Summer Sunrise to Winter Sunset) which is wrong. The Altar Stone is actually at 80° to that axis.

The angle between the two solstice sunrises' and the two solstice sunsets' positions, at the latitude of Stonehenge, in 2500BC - was 80°.

The primary axis and the secondary axis intersect directly over the centre of the Altar Stone.

Plan of Stonehenge showing primary and secondary solstice axes intersecting over the Altar Stone

I am convinced that the Altar Stone was deliberately placed prone and at 80° to the main solstice axis of the sarsen phase of the monument, by the builders, in order to encode the secondary solstice axis of Winter Solstice Sunrise to Summer Solstice Sunset.

There is other evidence that supports the idea that the 80° angle is not accidental. In 2014 Tim Daw wrote about the "Twisted Trilithon" (the tallest one) of stones 55, 56 and 156 also having this angle to the primary axis, with a sightline along the SW face of 56 being aligned to the Winter Solstice Sunrise/Summer Solstice Sunset. Tim provides further evidence in his paper concerning other features of the site that share this 80° orientation.

Objectors to the secondary alignment sightline I've described above might point out that stones 57, 58 (with its notch) and their lintel 158 were re-erected in 1958 having fallen in 1797, and suggest that they might have been put back "wrongly". I dispute this - Atkinson, Stone and Bailey plus their team went to extraordinary lengths to re-seat the fallen stones correctly in their original stoneholes, even going to the effort of taking plaster casts of the bases of the stones and their stoneholes to correctly position them in their new concrete footings.

Objectors may claim that the notch is a convenient natural coincidence. I also dispute this - close inspection of it, and comparison with another notch higher up on the same edge of the same stone, suggests to me that the alignment notch shows evidence of having been tooled to smooth its natural shape into one that suits the alignment more perfectly.

Objectors might also deny that the builders of Stonehenge were at all interested in the Winter Sunrise/Summer Sunset on the basis that the entire monument has a very obvious and striking focus on the Winter Sunset direction (citing the form of the trilithon horseshoe and the impressive NE front of the sarsen circle that almost forces the viewer to want to look at things from the NE towards the SW. I do not consider that the designer of such an exquisite structure would overlook encoding the companion alignment to the obvious one we all accept, albeit in perhaps a more subtle way.

Finally, I leave you with the following images of the astonishing Bush Barrow Lozenge excavated from a bronze age barrow within sight of Stonehenge towards the southwest, whose design also captures that hallmark 80° angle of the Sun's extreme positions at the latitude of Stonehenge, and a view of the winter sunrise through Stonehenge along the secondary solstitial alignment axis.

The Bush Barrow Lozenge in Wiltshire Museum, Devizes

Stonehenge plan, solstice axes and the Bush Barrow Lozenge

Near Winter Solstice Sunrise along the Secondary Alignment

Wednesday, October 14, 2020

C.A. "Peter" Newham and the Station Stone Rectangle

There's an excellent little book by C.A. "Peter" Newham called "The Astronomical Significance of Stonehenge" (originally published in 1972) in which he lays out his ideas about the monument, and specifically a new thought about the possible Lunar significance of the Station Stone Rectangle.

What's not as readily available is the first publication of his ideas, which occurred in an article written by Science Correspondent Douglas Emmott in The Yorkshire Post on Saturday March 16th 1963.

The article is entitled "The Mystery of Hole G", and I've been trying to find a copy of it for years without success. Until today, when the local and family history librarian at Leeds Central Library, Helen Skilbeck, kindly sent me a scanned copy from their archives of The Yorkshire Post.

I've reproduced the text of the article here for posterity.

The Mystery of Stone G

========= BY DOUGLAS EMMOTT =========

Attention this week has once again been focused on Stonehenge, where one of the uprights was blown down in a gale.

In this article, The Yorkshire Post Science Correspondent discusses an amateur astronomer's intriguing theories which may add a new chapter to the story of Stonehenge.

STONEHENGE, that mysterious monument which rises above Salisbury Plain, may be a little less inscrutable than had been supposed.

An amateur astronomer, Mr. Peter Newham, 63, of Tadcaster, has formulated an intriguing hypothesis which, if proven, might open up whole new fields of inquiry in a subject which has yielded very little significant new information since the last major excavation nearly 40 years ago.

If Mr. Newham's line of reasoning is sound, the positions of certain hitherto inexplicable features of Stonehenge would be explained.

For the purposes of this inquiry the plan of Stonehenge given here is reduced to the elements bearing upon the new theory.



In 1846, the Rev. E. Duke discovered that the North mound 94 lined up with a stone numbered 93 at the last light of the setting sun on the shortest day of the year. Conversely, a line drawn from the South mount (92) to stone 91 aligned with the rising sun on the longest day of the year.

It was discovered, too, that the axis of the Sarsen stone circle was similarly aligned. In fact, the positions of sunrise and sunset are slightly different today owing to the progressive shift of the earth's axis.

So much, then, is established. What follows is speculation. On several occasions in the past few years Mr. Newham has visited the site and made careful observations of his own.

The first remarkable discovery he made was that a line drawn from mound 94 to 91 would appear to coincide with the point on the horizon where the moon rises at its most southerly point during its 19-year cycle.

Conversely, the line from 92 to 93 marks the moonset at its most Northerly setting point. The suggestion that these two alignments are of significance is bolstered by the curious fact that the main Sarsen circle of stones is about a yard off-centre with the outer Aubrey circle of burial holes.

Had it been quite concentric, the 92-93 sighting would have been obscured. Is this the reason for the off-centredness which has puzzled generations of archaeologists?

It must be remembered that the layout of Stonehenge has been drawn up generally with remarkable precision. The ancient architects were evidently knowledgeable geometricians: indeed, the feat of measurement would tax a modern surveyor with the most up-to-date instruments and techniques.

Unusual feature

From this point, attention is turned to another unusual feature. This is catalogued as "hole" G, the middle of three equally spaced "holes" lying to the East and just beyond the Aubrey circle, and for which there is no convincing explanation.

Most Stonehenge authorities have dismissed these disturbances as natural or "shrub-holes." Their disconcerting symmetry and the absence of similar features within the whole of the area that has been uncovered have prompted doubts in more cautious minds.

Mr. Newham has noted that a line drawn from 94 to G appears to mark the rising sun on the shortest day of the year. Mound 92 to G marks the moonrise at its most Northerly point.

Thus, six of the eight major solar/lunar events of the year are apparently accounted for within the theory. To complete the octet, Mr. Newham has postulated the existence of a further marker hole in the unexcavated part of the site about 16 yards South of 93. This he has provisionally designated G2.

Now, a line drawn from 92 to G2 would mark the setting sun on the longest day, while 94 to G2 would mark the moon set on its most Southerly point. Thus, the hypothesis has the added merit of inviting confirmation. If the hypothetical G2 should, in fact, be discovered the possibility of coincidence could be virtually eliminated. The key which now seems to fit the lock would surely turn.

Advanced culture

It would seem, therefore, that Stonehenge might be a far more comprehensive calendar in stone than has been supposed. This, in turn, would suggest that the builders of the later portions of the monument were of a more advanced culture than the native inhabitants of Britain at that time says Mr. Newham. There is supporting archaeological evidence for this view.

A few years ago, there would have been no difficulty in obtaining permission to search for positive confirmation of the existence of G2. One would simply have dug about the point indicated and sought the necessary proof.

Today, however, archaeologists tread with infinite care. In the past, crude pickaxe excavating has destroyed a wealth of detailed information which modern science would have been capable of deciphering. Such brutal methods have wrought such havoc with the "shrub-holes," for example, that it is now almost impossible to determine their real significance even with advanced techniques.

Reluctant to dig

Conscious of this fact and realising that future generations of investigators will read much greater meaning into undisturbed evidence than we might hope to do, the custodians of Stonehenge are reluctant to dig. Nearly one half of the site remains virtually unexplored below ground and only in exceptional circumstances will the Ministry of Works sanction further excavation.

It is conceivable, however, that archaeological advisers will recommend a search for Mr. Newham's ghost-hole, G2 by preliminary above-ground detection methods. Encouraging soundings would indicate a call for spade and trowel - and, perhaps, the opening of a new chapter in the story of Stonehenge.


Friday, July 24, 2020

Avenue Walk and the Durrington Walls Pits

In mid 2020, the Stonehenge Hidden Landscapes Project published findings from their extensive geophysics work in the World Heritage Site in which they revealed the discovery of "A Massive, Late Neolithic Pit Structure associated with Durrington Walls Henge" (

This is a roughly circular arrangement of 10m wide by 5m (at least) deep pits centred on Durrington Walls with an overall diameter in excess of 2km - a truly enormous landscape feature.

The discovery has already prompted a remarkable event - the deferring of the decision by the UK Government's Transport Secretary, Grant Shapps MP, on whether to build the Stonehenge Tunnel. As this BBC News Story highlights, such a major find within the Stonehenge World Heritage site, very close to the proposed location of the Tunnel's Eastern Portal entrance, means that "further consultation" is required.

The decision has been put back until November 2020 to allow time for an analysis of the significance of this completely unexpected archaeological result.

LIDAR of Durrington Walls overlaid with the pit circle locations
I found myself wondering whether there was any significance to the arrangement and positioning of these "pits", but couldn't see anything obvious from the plan.

Then I decided to stop looking at the plan, and instead look at the landscape from ground level.

I georeferenced the pit locations into Google Earth, stuck markers in them, and took a virtual stroll along the course of the Stonehenge Avenue from West Amesbury Henge (aka Bluestonehenge) at the River Avon towards Stonehenge.

What I saw astonished me.

The pit locations occupy positions that serve to frame the eastern horizon from Larkhill Causewayed Enclosure via Sidbury Hill to the northern ridge running from Beacon Hill.

Each of these horizon features was important in the Neolilthic.

Larkhill Causewayed Enclosure 

Larkhill's enclosure pre-dated the Durrington Walls pits by almost 1000 years yet it is included in their circuit. Later Beaker period inhumations at the entrance, together with a pit alignment pointing off towards Barrow Clump and Sidbury Hill suggest strongly that this site retained its significance for generations.

From the Intarch article above:
"Monuments may have formalised or commemorated movements and gatherings of different scale, though the emphasis on localised patterns of visual perception perhaps relates to movements around the landscape at a community scale."

Sidbury Hill

Sidbury Hill lies exactly on the Stonehenge summer solstice alignment from the stone circle, and appears to have been important as a source of a particular kind of flint associated with dozens of neolithic pits and a flint working industry discovered during the Army Rebasing Housing Development at Bulford.

Those pits contained an odd assortment of apparently deliberately deposited artifacts, and next to them was a peculiar "double henge". Opposite the housing development is the Bulford Stone - a natural sarsen boulder which was erected next to where it originally formed on top of the chalk, and next to it is a prehistoric grave which contains significant and unique grave goods.

Phil Harding (recognised as the leading expert on prehistoric flint working) regards the Bulford pits and double henge discovery as one of the most significant for decades. Sidbury Hill seems to have been of pre-eminent importance and focus to these neolithic people, and also to those who came later because three long Bronze Age linear ditches converge at Sidbury Hill - one from the west, one from the north and one from the east.

Beacon Hill Ridgeline

The ridge leading to Beacon Hill has been cited as a possible target for the alignment of the Stonehenge Greater Cursus. Although this earthwork monument runs roughly west-east, it is not accurately aligned on the equinox sunrise and set. Instead, it seems to be drawing attention to the eastern horizon, particularly the area immediately north of the summit of Beacon Hill.

In alignment with and east of the Cursus, between the Cursus and the River Avon, lies the Cuckoo Stone near to Durrington Walls itself. This stone is another natural sarsen boulder which was erected next to where it formed. It seems to have retained its importance down to Romano-British times as the discovery of the square Roman "wayside temple" right next to it indicates.

The Avenue Walk

Larkhill enclosure, Sidbury Hill and the Beacon Hill ridge are the primary features of the horizon that are framed by the Durrington Walls pit locations as you walk along the Avenue.

At every point along this route, the arrangement of pits neatly brackets this section of the horizon - the arrangement of pits in a circle neatly counteracts the parallax effect that an otherwise straight-line arrangement would suffer.

Once you reach King Barrow Ridge and Stonehenge comes into view, the eastern horizon frame fades away as you descend into Stonehenge Bottom and begin your final approach to Stonehenge itself.

Now that you have the background, have a look at the video I've created that shows the effect.

This video (which has no audio, by the way) makes use of Google Earth, into which I have georeferenced the locations of the Durrington Walls pits from the Stonehenge Hidden Landscapes Project's recently published paper about their discovery. The line of the Avenue itself is taken directly from the Stonehenge Riverside Project's "Seeing Beneath Stonehenge" Google Earth dataset. Markers for Sidbury Hill and Larkhill Causewayed Enclosure were added by me.

It's best viewed full screen on YouTube (, but here's an embedded version. (Update: I've added a commentary in the subtitles, so remember to switch them on before viewing)

Is it possible that the entire landscape is repeatedly and deliberately being memorialised by generations of ancient people through the careful framing of and drawing of attention to elements of their world that have achieved "specialness" through aeons of time?

I think so.

This, if true, indicates an outstanding aesthetic sense and a desire to undertake "landscape engineering" on an absolutely epic scale. It shows an interconnectedness not only in space but also through immense spans of time, reinforcing a people's relationship with the land and their past.

What I find most interesting is that the route of the Avenue has been a subject of controversy for a long time. It's not the easiest stone-transport route from the Avon to Stonehenge, but seems instead to have been designed (at the depths of the valley at Stonehenge Bottom) to induce a sense of expectation prior to the final approach along the solstice axis to Stonehenge. Indeed, at that final turn (the "Elbow"), Stonehenge disappears from view entirely, only re-emerging as you climb the slope towards the setting winter sun.

The part of the Avenue route leading from the Avon to King Barrow Ridge now seems to me to have its own crucial significance - keeping in clear view all the parts of the eastern horizon that have a meaning to those undertaking the journey.

Perhaps, given the idea that the Avenue was part of a ritualised journey from life to death from Durrington Walls to Stonehenge, this sharp focus on a particular sweep of the eastern horizon serves as an act of rememberance of all those who have gone before.

And those pits don't even have to be visible for that to happen - just an understanding that they are there and that they are positioned to induce this feeling would be enough.

What a majestic achievement, still appreciable across open farmland nearly 5000 years after it was laid out.

Pity it might all be spoiled by driving a 4 lane expressway directly through the critical part of the view.

Update: 11th August 2020 

Professor Vince Gaffney has kindly given me permission to include an animation that was generated using the software that accompanied the 2000 Archaeopress publication "Stonehenge Landscapes: Journeys Through Real-And-Imagined Worlds" (Exon S, Gaffney V, Woodward A and Yorston R).

 It shows the viewsheds and monument visibility that develop from the point of view of someone walking the line of the Avenue from the River Avon to just beyond King Barrow Ridge.

 (Credit: R. Yorston. Major monument animation from Exon et al. 2000. Stonehenge Landscapes)

Monday, June 22, 2020

The Shadow of the Heelstone

The most commonly known thing about Stonehenge is that it lines up with the Summer Solstice sunrise and Winter Solstice sunset.

In summer, celebrants gather in their tens of thousands to spend the night in and around the stone circle hoping to see the Sun rise over the Heelstone.

But it may be that everyone is facing the wrong way by looking at the Sun and they ought to be facing the other way and watching a shadow play instead.

In the early 1990s, Professor Terence Meaden rediscovered an almost totally forgotten aspect of the monument and published his findings in a book called "The Stonehenge Solution" (Souvenir Press, 1992).

He said that the Heelstone cast a shadow at dawn on the summer solstice which penetrated into the stone circle and reached the Altar Stone. This, he wrote, represented a sacred marriage or "hieros gamos" of the Sun and the Earth. The Sun God at the height of his power was fertilising the Earth Goddess by means of the Heelstone shadow - the Earth Goddess being represented by the stone circle and its central horseshoe of trilithons.

An intriguing idea, and not without precedent in societies where human participants take part in and facilitate such ceremonials both in ancient and modern times.

Is it a coincidence that 9 months after summer solstice comes the vernal equinox, when the Earth erupts into vibrant life once more?

In 2013 I was able to capture an image of the Heelstone's shadow shortly after dawn on the 24th June.

05:14 BST, 24th June 2013
There are a couple of obvious problems with this photo - and it's not the people enjoying a ceremony in the centre.

The first is that it's a few days after summer solstice (21st June usually, 20th in leap years). This shouldn't be too much of an issue because the Sun's rising (and setting) position on the horizon stays almost exactly the same for a few days either side of solstice (it's what solstice means - "Sun stands still").

The second problem is more serious - the shadow is off to the right of the main entranceway into the stone circle, and as the Sun rises higher the shadow moves further to the right and grows shorter. Does this mean I should have taken the photo earlier, or that the whole concept is flawed?

Two major things have changed in the landscape since Stonehenge's large sarsen stones were put up 4,500 years ago.

One is that the horizon to the northeast in Larkhill is now cluttered up by a modern collection of trees exactly where the Sun rises at solstice. This delays the appearance of the Sun by almost 10 minutes, by which time it has moved upwards and eastwards.

The other is that the Earth's axis of rotation has changed its tilt a little. When Stonehenge was built, it was at 24° and now it is 23.5°. This slight reduction has caused the summer solstice sunrise position over an ideal horizon to move to the right (eastwards), by about 1°.

The combination of these factors mean that where once the Sun rose to the left of the tip of the Heelstone over a clear horizon, it now rises out of the tip and through trees - which is why the Heelstone's shadow doesn't seem to fall through the entranceway any more.

I can't do anything about the Earth's tilt, and although I'm trying it's not easy to persuade the military to expend resources felling trees on their estate to clear up the Larkhill sightline.

What I can do is to try and take photos closer to the actual solstice day than the 24th June, to see if the shadowplay improves at all. A clear-to-the-horizon sky within a day either side of summer solstice is rarer than you might think. The few occasions I've seen one have mostly coincided with the actual solstice day, when upwards of 10,000 people are standing exactly where the shadow should fall.

June 2020, however, has been different. The Covid-19 lockdown has meant Stonehenge has been entirely off-limits to early morning inner-circle visits (so no ceremonies), and the usual Open Access at summer solstice was cancelled with a security presence on site to discourage anyone attempting a large gathering.

This morning, the 22nd June, was happily clear of clouds and people and so I walked to Stonehenge to attempt to photograph the Heelstone shadow.

A mist lay in the Avenue field but not the rolling fog that so often billows around the monument when everywhere else is clear.

At 05:02:17 BST, the first gleam of the Sun appeared through the treetops at Larkhill.

First gleam at 05:02:17 BST - a tiny pinprick of light through the treetops of Larkhill

11 seconds later the upper limb of the Sun emerged.

Upper limb appearance at 05:02:28 BST

The timelapse of 100+ photos taken over the next 15 minutes revealed some useful information.

Although it is practically impossible to see without processing the image to stretch the contrast, the Heelstone shadow is present in this photo. It's not visible on the ground, but on the lower left side of the face of Stone 30 - the stone on the right hand side of the entranceway into the stone circle.

First sight of the Heelstone shadow - yes, I know you can't make it out in this unprocessed image!
This next image has been very heavily processed - I have massively increased the saturation to highlight the difference between the reddish-pink stones glowing in the light of the rising Sun and the more neutral gray colour where the shadow lies. This is not simply an area of the stone that's not facing the Sun (because it is facing the Sun), as you'll see later.

The lower left corner of Stone 30 is in shadow - the Heelstone's shadow
As time went on, minute by minute the shadow became more distinct. By 05:09:17 it was obvious, both on the face of Stone 30 and also on the grass.

The Heelstone's shadow is now visible on the grass, and the tip of the shadow on Stone 30 has moved to the right
At 05:14:10 we're at practically the same moment as my 2013 photo, and the Heelstone shadow is just about to leave the base of Stone 30.

The same clock time as in 2013, but two calendar days earlier (22nd rather than 24th June)
The caption above says "two calendar days earlier" - in fact it's one actual day earlier because this year is a leap year and 2013 wasn't. Today would be the 23rd June if 2020 wasn't a leap year. It's matters like this that archaeoastronomers lose sleep over.

I stopped taking photos from this position at 05:16:55 as by then the shadow had moved off the stones entirely, and I had what I needed.

05:16:55 BST
What does all this prove?

The key thing is that the tip of the Heelstone shadow is at least 1m above ground level when first seen on the face of Stone 30.

This means that the shadow definitely penetrates into the stone circle and must reach the Altar Stone. This is a secondary confirmation since if you lie down inside the circle with your head on the Altar Stone looking towards the Heelstone you can see that the Heelstone tip is above the horizon line (the tree-lined one, and therefore also the actual horizon).

4,500 years ago, without trees and with the Earth's axis at 24°, the Sun would be fully risen by the time the tip of the Heelstone shadow coincided with the primary axis of the monument and so a strong and clear shadow would be visible running from the Heelstone up to and into the circle.

Terence Meaden's work is confirmed.

I'm very glad to have been able to help cross-check this shadow play phenomenon, and Terence has now got copies of all the photos I took this morning so he can do his own processing on them. His recent work on the stone circles of Ireland shows that similar shadow play is evident there too (see "Stonehenge, Avebury and Drombeg Stone Circles Deciphered" for more details), and he's moving on to investigate the Cornish ones.

It's beginning to look a lot like the builders of these monuments encapsulated the movements of the Sun with an incredible subtlety that we are only now starting to appreciate.

My time-lapse movie (together with explanatory notes) is available on YouTube at, and I've also embedded it below for your convenience.

I hope you've enjoyed this excursion into experimental archaeoastronomy.

Additional note: when researching a topic related to the traditions associated with Stonehenge, I happened across a passage in Gerald Gardner's 1959 book "The Meaning of Witchcraft" (Aquarian Books, 1959, p40) which reads:
“At any rate, according to the witch beliefs the inner “horseshoe” of stones at Stonehenge represents the womb, and what should be watched for at sunrise at the Summer Solstice, the longest day, is the shadow of the Hele Stone which enters this “womb” as the sun rises and fecundates it for the coming year.”

Consulting with Terence, he was unaware of this earlier reference and so it seems that some otherwise "lost" knowledge of Stonehenge has been preserved amongst the followers of the Old Ways. I'm not at all surprised.