Culture

Sighthill Observations

by Duncan Lunan

Circle and Duncan Lunan Mar 2011, by Linda Lunan, Glasgow University at rear.

Readers of The Orkney News who also read the Glasgow Times  (formerly the Evening Times)  may have been surprised to see an article on 17th February claiming that I’d got the alignments of the Sighthill stone circle wrong, when I designed and built it in 1978-79, and in 40 years nobody visiting the site had noticed the errors.  Few people could have been more surprised than Dr. Kenny Brophy of Glasgow University, ‘the Urban Archaeologist’, who was named in it.  He protested strongly to the paper and asked them to change the headline and the opening sentence of the article, at least in the online version, but only the headline was altered.  Several other papers picked up the story, but there hasn’t been any feedback as yet.

The claim is of course ridiculous.  Thousands of people have visited the circle since it was built in 1979, and the reason none of them noticed that it was wrongly aligned, is that it wasn’t.  The offending article was supposed to be about how Kenny had headed a team of students in a survey of the circle’s new site, in September last year.  Instead the story cribbed from an article that originally appeared in the Daily Mail in 2015, after a very good article by John Reppion had appeared in the Fortean Times in October 2014.  The Mail reporter interviewed me by telephone about possible changes in the circle design, but then took the line that I’d got it all wrong in the first place, and that nobody had noticed in all the years since.  That despite the fact that I’d written up the solar alignments for the Griffith Observer in June 1986, and published updates in several other magazines meantime.

The Sighthill circle was built under the Glasgow Parks Dept. Astronomy Project, which was part of the Jobs Creation Scheme in 1978-79.  I was Project Manager, with the late John Braithwaite  (later the last telescope maker in Scotland)  as Technical Supervisor, and Gavin Roberts  (later Principal Teacher of Art at Airdrie Academy)  as Art and Photographic Supervisor.  The brief was to build a working replica of an ancient site, in modern materials, and because of the changes in the sky over the last 3-5000 years, I had to convince the Parks Department and the Manpower Services Commission to let me find a suitable site, and design a working monument for the present day, according to the ancient principles.  I then proposed to build it in stone, and dedicate it to Prof. Alexander Thom, Dr. Archie Thom, Dr. Euan MacKie and Prof. Archie Roy – all of Glasgow University and with major achievements in the field.  The site I chose was in the new Sighthill Park, due north of the city centre and overlooking the M8;  the stones came from the ‘Back o’ the Hill’ Beltmoss Quarry in Kilsyth, and the circle was completed at the spring equinox of 1979 by a Royal Navy Sea King helicopter from the HMS Gannet Naval Air Station at Prestwick.

The winter of 1978-79 had been particularly bad, with the worst storms of the century in the English Channel and major blizzards in Glasgow, so despite repeated attempts on site we had not been able to complete a survey of the astronomical alignments until February 23rd.  That pinpointed only the theoretical positions of the Sun and Moon’s risings and settings, as if the Earth were a perfect sphere with no horizon features and no atmosphere.  I still had to calculate the rising and setting tracks, by spherical trigonometry, to overlay on the ‘working photographs’ and find out where the tracks crossed the horizon.  Assuming three calculations for each of the 14 events, taking 2-3 pages each, there would be 42 pages of mathematics and then a graphical calculation for each, factoring in parallax and atmospheric refraction.

Meanwhile negotiations had been continuing about the possible use of a helicopter.  The Navy was keen to do it as ‘a weight-training exercise in urban conditions’ which normally wouldn’t be allowed, but the Ministry of Defence was against it.  My boss Ken Naylor mobilised his political contacts and the objections were removed, but at that point, due to other commitments, 819 Squadron could give us only two weeks’ notice of the operation.  I hadn’t even begun the calculations, and Ken Naylor made matters worse by demanding that everything must be on his desk by 10 a.m. the following day.

It took me all night to do it, helped by Tony Crerar  (aka Tony Marchet, mime artist with Hawkwind), megalithic expert from Wales, who happened to be visiting me and had given an impromptu performance at the Troon Folk Song Club that night.  There was no alternative but to cut corners, concentrating on the graphical calculations and making assumptions about the rest.  Specifically, I had to assume that the angle the tracks made with the horizon would be the complement of the city’s latitude, and I knew that was only an approximation, because it was treating the calculation as a plane triangle and not a spherical one.  Likewise I had to assume that the rising and setting tracks would make the same angles with the horizon all the way round it, and I knew that wasn’t true, because the Earth is a sphere and not a plate.  But I had to hope that the approximations would not be so far out as to make a big difference.

Original Sighthill circle alignments, by Dave McClymont, 1979

After I handed over the results the following morning, I went home to bed.  Ken had the grace to say, “I didn’t know how much work there was in this”.  In theory, I might have recalculated all the alignments before the helicopter operation, but in that time I had to arrange insurance for it, make arrangements with the fire and ambulance services, check out possible landing sites in case the helicopter had to refuel, organise an exhibition, press conference and reception, liaise with the BBC and STV, organise the time capsule as a rush job, and much more, culminating in a major meeting of all concerned parties on March 16th.  Without the help of Tom Bradley of Manpower Services Commission liaison, Alan Montgomery, the Special Project Operations Manager, Pia Pisaneschi, the Special Projects Secretary, Frank O’Neill, Special Projects Clerk of Works and Shop Steward, and many more, it could never have been done at all.  All we lacked was Tony Robinson running about shouting, “And we only have three days in which to do it!”

On the day, once we pulled it all off, I did multiple radio, TV and press interviews, the last of which was with Dave Jamieson of Radio Clyde – which went well enough that I had a monthly astronomy spot with him for 18 months afterward.  Having established that the whole thing had been done by calculation, and the stones were now cemented in place, he asked when the first confirmation of the accuracy would be – midsummer sunrise, in three months’ time.  And if the Sun didn’t rise in line with the stones, what then?  “I don’t know about the rest of them,” I replied, “but I’m for South America.  I might be able to flannel it with the Parks Department, but never with Professor Thom.”

Megalith0173B midsummer sunset 1992, Credit Duncan Lunan

The key events marked by the stones were the midsummer sunrise and sunset, midwinter sunrise and sunset, and the flanking major and minor risings and settings of the Moon.  For those lunar events, Prof. Thom had coined the term ‘standstills’.  I wasn’t keen on that, because the Moon doesn’t doesn’t actually stand still on those occasions, like the Sun for Joshua:  what it does is to reverse the direction in which its rising or setting moves along the horizon from one night to the next.  I preferred ‘maximum’ and ‘minimum’ and ‘secondary maximum and minimum’, but Prof. Thom didn’t like those and as everyone else used his terms, I took to doing the same.  I also marked the rising of Rigel, at the foot of Orion, for 1800 BC and the present.  My idea was that if some latter-day Gerald Hawkins ran the alignments through his computer, found Rigel at both dates, it would lead him to probe the ground and find the concrete foundations;  realising the central one was elongated would then lead him to the time capsule.  But over the years I’ve realised that the historical alignment was the only one people didn’t ‘get’, so in the new circle I’ve reused those stones to mark the equinoxes.

Rigel risimg over marker stone, to right of Townhead Church spire, 30th Nov 2009, by Mark Runnacles If you enlarge the photo, Rigel is the white dot to the right of the tower block, top right of the marker stone.

Over the years I’ve accumulated an archive of photos to find out how well the events matched the predictions, and as I said last week, it was only in 2018 that the new ‘Interactive Sky Chart’ on the Heavens-Above website  (www.heavens-above.com)  gave me a relatively quick and easy way to reconcile them, in increments of a minute of arc and a minute of time.  While waiting for the reopening of the circle, which is still fenced off by redevelopment contractors, I can put paid to the Mail and Glasgow Times calumny with the results, as follows.

Midsummer Sunrise was clouded out in 1979, but four days later I glimpsed a fan of light above the setting Sun which told me that it was at least in line with the stone.  For reasons which I’ve described in The Stones and the Stars, it wasn’t until 1992 that I finally got a clear view of it, witnessed by John Stark of the Kirkintilloch Band.  The sunrise was significantly to the right of prediction – though still in line with the stone.  The late John Braithwaite was sure that must be due to atmospheric refraction, and I reported it that way in the book, but eventually I realised that couldn’t be true.  Refraction, the effect that makes a stick look bent when half-immersed in water, always acts upwards.  Warmer air or denser air can raise the apparent position of a body near the horizon, but cold air can never lower it below its true path.  My calculated position for the midsummer Sun on the true horizon was correct, but the angle the rising track made with it was slightly less than I thought – moving it right on the skyline by a degree and a half.  That’s less than a finger’s breadth at arm’s length, but it makes a difference of three solar diameters.

Midwinter sunrise over marker stone, 1979, by Gavin Roberts.

Midwinter Sunrise was first observed and photographed by Gavin Roberts in December 1979, and seemed to be exactly as predicted.  However, that was through the thick industrial haze which then hung over the Clyde Valley for much of the time.  Some years later, on a very cold morning and after the steelworks closed, I saw the Sun rise several diameters to the right.  Again I thought that was due to refraction, but actually the true rising path is lower than I predicted – but still in line with the stone.

Midwinter sunset shadow of central stone on midsummer marker, 1982, by Duncan Lunan

Midwinter Sunset was first photographed by myself in December 1982, witnessed by the late Prof. Oscar Schwiglhofer, and was by St. Andrew House as expected, but the track was half a degree higher – due to refraction, but the track was again shallower than predicted.  Nevertheless the shadow pattern was as planned, with the marker stone’s shadow falling on to the central stone, and the central stone’s occluding the midsummer sunrise marker across the circle, even though they aren’t exactly opposite, as Prof. Thom had pointed out with some force when he saw the draft layout.

Enhanced midsummer sunset, Sighthill circle,1981, Ben Lomond to right, by Duncan Lunan

Midsummer Sunset was photographed in 1981 by myself, and definitively in 1986 by Chris O’Kane, later President of the Astronomical Society of Glasgow. 

Midsummer sunset clearing the White Horse Distillery, 1986,, by Chris O’Kane

I had predicted that it would set on the roof of the White Horse Distillery, but in fact it cleared the roof and set on the natural hillside to the right.  Again refraction was mainly to blame, but the predicted track was slightly too low.

Major Standstill North Moonset was witnessed by myself and photographed by Mark Runnacles of the Daily Record in February 2006.  The track was slightly flattened by refraction near the horizon, but the event was bang in line with the stone.

Major standstill north moonset, 9th February 2006, over marker stone, by Mark Runnacles

Major Standstill South Moonset was seen and photographed by us both in August 2007.  Again the track was lower than expected, and flattened, but the setting was in line with the stone.

Major standstill south moonset approaching marker stone, 23.8.07, by Mark Runnacles

Major Standstill South Moonrise was witness by myself and Desi Atkinson of the Fortean Society in winter 2006-2007.  I didn’t have a suitable camera with me, but the moonrise was spot on.  My colleague Bob Graham of the North Lanarkshire Astronomy Project tried again with me in July 2007, but the Moon didn’t break free of the clouds till it was at peak altitude.

Major Standstill North Moonrise was predicted to occur between two of the Sighthill High Flats, before their demolition, but when it was photographed by Mark Runnacles with me in September 2006, again the rising track was lower than expected.  Although John Braithwaite disagreed, when the Moon came out from behind the tower block it was at too high an altitude for refraction to explain the difference.

Major standstill north moonrise emerging behind Sighthill flats, 15.06.2006, by Mark Runnacles

Paul Benson, then a curator of Airdrie Observatory, had tried to photograph Rigel rising in the early 1980s without success, and we concluded that it might never be possible due to light pollution.  By 2009, however, Glasgow and North Lanarkshire had adopted a dark-sky compatible lighting policy, and in November 2009 we photographed Rigel rising in a blue night sky, where in 2006 it had been orange.  The Townhead Church, on the end of which it should have risen, had been demolished by then, likewise the tower block behind it, but the spire remains and on the true horizon the star would be at the base of it.  But the predicted track was again too high, and refraction can’t be blamed for that.

Minor standstill south Moonset passing over marker stone, 2014, by Mark Ferrier

The last observations taken are most mysterious of all.  Minor standstill moonrise and moonset had consistently eluded me – a year either side would suffice to prove the relative accuracy of the alignments, but the events occur only every 18.61 years, and in 1997 I was working as a precognitions agent for a defence solicitor and couldn’t fit in my plans with the movements of the Moon at all.  Due to weather, the only successful attempt at photography was by Mark Ferrier, in my absence, who captured the minor southerly moonset in October 2014.  The Moon sailed over the stone and sets about a degree to its right, the only event that wasn’t directly in line.  The stone could be out of alignment, but all the ones in the southerly arc were positioned by Gavin Roberts and the rest are spot on.  Alternatively, the entire sequence takes place within five degrees of the horizon – half a fist at arm’s length – and it was a foggy night, so the raised track could be due to refraction.  There was no other opportunity to check before the stones were removed in 2016.

I should emphasise that this is just a record of the successful observations, and a great many more were not.  For example, Chris O’Kane and I had tried to photograph moonrise at its furthest north throughout the major standstill of 1987, whenever we could get there, but the weather foiled us every time.  Just drawing and redrawing the tracks to reconcile the Interactive Chart numbers with the photographs was a big task.  When I finished, and had transferred the tracks to the new ;working photographs’ to determine the new alignments, it was all looked over by Dr. Alan Cayless, former curator of Stirling Observatory, senior tutor in Physics and Astronomy with the Open University, and responsible for maintenance of their remote telescopes on Tenerife.  I mentioned that he was looking at only the fair copies of the results, and he replied, “Yes, I can see that by the number of times your printer has run out of ink!”

When I first formulated the circle’s design, I made sure that every feature of it was found on some ancient site – partly to fulfil the original brief, but also to make the point that it was functional as an observatory in the present day.  Anyone maintaining that the ancient sites were not observatories, should have to explain where the difference lay.  But as a result of the observations, I can now answer a more fundamental point.  Because of the slight but significant changes in the sky since the Neolithic, it has been possible until now for critics to say that the accuracy claimed by Prof. Thom could never be achieved by naked-eye observation.  The Sighthill events clearly show that if we were using distant ‘foresights’, as at the ancient sites, and we compiled years or decades of observations before we put the stones up, it could certainly by done by eye alone.

As Dr. Cayless pointed out when he heard about the Glasgow Times attack, the fact that the new new site alignments are more accurate does not make the previous ones ‘wrong’ and the new ones ‘right’, only better.  Assuming that nothing went wrong during the re-erection, the new events should all be in line with the stones  (centrally, I hope).  But there is one reason why they still might not be.

Midsummer sunset going into cloud, nearing new site horizon, 28.06.19, by Duncan Lunan

In my original calculations, I had inserted into each a mean value for atmospheric refraction, taken from tables in Thom’s books.  The actual situation is rather different.  None of the rising events, the ones on the east side of the circle, show any refraction at all.  If there is any, it’s so slight that it’s hidden behind the buildings on the skyline.  The major standstill settings on the west side of the circle show very little.  Yet the three sunsets – midwinter, midsummer and the equinox, which my wife and I observed and photographed in March 2011 – show marked upward displacement, starting well above the horizon.  It’s not an effect of temperature, because the three events cover the whole range of the solar year, and they all show upward displacements of 1.5 to 2 degrees, near the maximum theoretical value. 

To see that and measure it, of course, requires a clear day.  It looks as if we’re seeing a change in the air over the city – probably due to the formation of smog, due to the action of sunlight on car exhaust fumes.  Without intending to, it looks as if we have created a new measure of air quality and pollution.  How significant that will be, in the longer term, remains to be seen.

2 replies »

  1. Both utterly fascinating and astonishing, Declan. The work put into this project by you and others is remarkable, and I salute you all for this in admiration, particularly given the demands.

  2. “cribbed from an article that originally appeared in the Daily Mail”

    Daily Mail? ‘Nuff said.