What does the new henge mean for Stonehenge?

Confusion at Stonehenge
Confusion at Stonehenge

Confusion at Stonehenge

I don’t know.

I think the cov­er­age at places like the BBC are good, David Gregory found it excit­ing and I thought his story was a good read. However there are too many details miss­ing from the reports to come to any con­clu­sions. That’s not a com­plaint about the cov­er­age, the mass-media isn’t an archae­olo­gical journal. It’s not even a gripe about pub­lic­a­tion by press-release because Mike Parker Pearson showed last year that news leaks out, so why not give the brief details out properly?

On the other hand the Birmingham team are look­ing at the land­scape and, from read­ing the reports, I’ve no idea where this new site is in rela­tion to Stonehenge. It’s almost cer­tainly in sight of Stonehenge, but then the land­scape round there is littered with bar­rows, Bronze Age burial mounds. The loc­a­tion will affect how we see the land­scape. This henge isn’t to be con­fused with Bluestonehenge, the site found by the river Avon near Stonehenge last year. It’s also not Woodhenge, des­pite being made of wood, because that’s a dif­fer­ent site near Durrington Walls, which is another site that has been in the news in recent years.

There’s not a lot I can say about the astro­nomy of this henge either. It could be aligned to the sum­mer sun­rise, but I can’t tell because the dia­gram doesn’t say which way north is. Also look­ing at the dia­grams, the stone circle seems to have entrances facing one axis and the tim­ber circle an entirely dif­fer­ent align­ment. In fact, the entrance to the wooden circle seems to be facing stones. To me, that sug­gests at least two phases to the monu­ment. I ima­gine that there’ll be some sort of test excav­a­tion along sim­ilar lines. If you want to take your time plan­ning an excav­a­tion it’s a very sens­ible idea not to flag up the loc­a­tion in the news.

Ground Penetrating Radar by Ben Urmston

Ground Penetrating Radar by Ben Urmston

The con­fu­sion that this find­ing is going to cause will be huge fun for Stonehenge watch­ers. The equip­ment they’re using is Ground-penetrating RADAR. This used to be rub­bish, some­thing you’d only use in an urban loc­a­tion where you got a good sig­nal, but as with everything involving a micro­pro­cessor it’s advanced massively. It means that there’s huge swathes of land where some com­pletely unex­pec­ted things will be found. In some­where as busy as the Stonehenge land­scape there has to be much more than this wait­ing to be dis­covered. It’ll raise some awk­ward ques­tions for archae­oastro­nomers, because des­pite there being align­ments will these newly dis­covered struc­tures have blocked the view?

The excit­ing thing about this work is that it shows not only to we not have all the answers, we don’t even have all the questions.

Photo credit: Ground Penetrating Radar photo by Ben Urmston.

Astronomy at Ston̈ehen̈ge for the 2010 Summer Solstice


I’ve been busy, recently and I’m likely to stay that way for a while, hence the lack of posts. Still, I’m hop­ing to be able to take a trip to Stonehenge this year to see the sol­stice. That’s why my pre­dic­tion is that it will be cold and wet and thick cloud will pre­vent any­thing inter­est­ing mak­ing an appear­ance. However, if there are clear skies, there could be plenty to see over Stonehenge this sol­stice.

Natural Astronomy

There’ll be plenty to see in the even­ing sky after sun­set at 9.26pm. To the west Venus will be extremely bright at mag­nitude –4.0 (the lower the num­ber the brighter some­thing is). When you see it you won’t be able to mis­take it for any­thing else. That will be set­ting at a quarter to mid­night, so there’ll be plenty of time to see it.

Stonehenge astronomical chart for sunset solstice 2010

Position of the plan­ets at sun­set. Click for full size.

Moving to the left, are Mars, Saturn and the Moon. Mars will be mag­nitude 1.3 so it won’t be the bright­est thing in the sky, Arcturus and Vega will be brighter but it’ll still be easy to find. If you’re strug­gling find the Plough. The two pointer stars that point up to the Pole Star will be more or less also point­ing down to Mars this even­ing. Mars sets at a quarter to one, but if you want to see it real­ist­ic­ally you’ll have to be look­ing before mid­night. If you’re lucky it’ll have a slight ruddy glow. Saturn will be the only bright object between Mars and the Moon. In fact it’ll be slightly brighter than Mars in per­fect atmo­spheric con­di­tions, but I doubt my eyes will be good enough to meas­ure that.

The Moon will be in Virgo, near the star Spica, which was thought to be a sheaf of corn in the hand of Ceres, if you’re Roman, or Demeter, if you’re Greek. Fans of myth­o­logy will be keenly aware that Demeter/Ceres had a daugh­ter with Zeus which makes her not tech­nic­ally a vir­gin, but the Greeks called her Parthenos and that usu­ally gets trans­lated as vir­gin. To find Spica usu­ally you’d fol­low the arc of the handle of the Plough to Arcturus, and then Spica is the next bright star down. This night it’ll be the closest bright star to the Moon. It could be hard to spot because the Moon will be bright. It’ll be 69% lit, nine days old and wax­ing gib­bous. It’ll be more or less low in the sky to the south at sun­set and set around 1am, which is astro­nom­ical mid­night. It’s not the same as civil mid­night because these days Stonehenge is on Daylight Saving Time, like the rest of the UK.

Stonehenge astronomical chart for midnight solstice 2010

Stars at 1am over Stonehenge. Click for full size.

Around 1.20am Jupiter rises. It’s likely that you’ll need to wait till 2am to get a good view. It’ll be shin­ing in sil­ver at mag­nitude –2.4 and, because Venus will have set, it’ll be the bright­est planet on the sky. Jupiter will have a part­ner, but it’s highly unlikely you’ll see it at Stonehenge. Uranus will be close to Jupiter. If you hold out your hand at arm’s length then Uranus will be five or six little fin­ger­nail widths to the right of Jupiter. Normally there’s no chance at all of see­ing Uranus, but at the moment it’s at mag­nitude 5.8 which puts it right on the limit of human vis­ion. If you have very good eye­sight and the atmo­spheric con­di­tions are per­fect you’ll see what looks like a very faint star next to Jupiter, and that’s Uranus. But even if we have that, I still doubt you’ll see it.

The reason is that it takes time for your eyes to adapt to the dark. Ian Musgrave says it takes a few minutes to see down to mag­nitude 5 or 6. Your eyes need to build up chem­ic­als to make them more sens­it­ive. Every time you see a bright light, like car head­lights from the nearby roads, torches from other vis­it­ors who — quite reas­on­ably — don’t want to break their necks walk­ing around and any light­ing from English Heritage this adapt­a­tion will be lost. On top of this there’s light pol­lu­tion. We don’t just use energy light­ing streets. A lot of energy is used to light up the sky, for no obvi­ous reason. This reflects from any water droplets in the atmo­sphere and gives a sodium glow to the sky. Even cit­ies over the hori­zon will be vis­ible by their light pol­lu­tion and this will pre­vent you from see­ing some of the stars. You’ll stand a bet­ter chance of see­ing Uranus if you use binoculars.

There is another difficult-to-spot object in the sky. To the north near Capella is Comet McNaught. Searching on the web for this is no help. There’s a lot of Comet McNaughts because Robert McNaught has found over fifty of them. This one is Comet McNaught 2009 R1. The cur­rent fig­ures I have are that it will be between mag­nitudes 5 and 6. If that’s the case then you might not see much without dark-adapted eyes and it’s a bin­ocu­lar object. This fig­ure is uncer­tain though because the comet is get­ting closer to the Sun. Around June 30-ish it’s pre­dicted to be as bright as mag­nitude 2. Capella is not too hard to find. It’s the only bright star above the north­ern hori­zon, and it will be due north around half-past mid­night. The comet will be a couple of degrees above it. Look for a fuzzy star.

The Sun is due to return a few seconds before 4.52am. Again, day­light sav­ing explains why the Sun sets less than three hours before mid­night, but doesn’t rise till almost five hours after.


Or, if you don’t tell your friends what they are, UFOs.

The big events will be the passes of the International Space Station. There’ll be two and half over Stonehenge. The first will be at 1.08am till 1.10am. You’ll be able to see the ISS drop­ping from 38º up in the sky to the south­east down to the hori­zon. It’ll be bright (mag­nitude –2.7) but it will also be fast. This is the half appear­ance and you may not see it. You best chance is to be look­ing at Aquila, the bright­est star in the south­east at this time, and it should appear near there.

The next appear­ance is the best. At 2.40am it will rise in the west and pass over­head before set­ting in the east at 2.46am. It will look like Venus did, but it will vis­ibly be mov­ing across the sky. It could look like an aero­plane and if any­one else says that you might want to agree before point­ing out that there’s no vis­ible flash­ing lights like there would be on an aero­plane. It will also be trav­el­ling too fast. Get your friends to rule out other obvi­ous causes like Chinese lan­terns, reflec­tions of head­lights, plan­ets and so on so that you sound like you’ve been reluct­antly con­vinced that whatever you saw was not of this world.

Then at 4.15am you can make every­one jump out of their skin by yelling “They’re BACK!” when the ISS makes another pass from the west again. This time it will set 4.23am in the eastsoutheast.

For extra UFO points you can also try point­ing out an Iridium flare. This is a sud­den bright reflec­tion from one of the Iridium com­mu­nic­a­tions satel­lites. There are two dur­ing the course of the night. At 10.52:44pm on June 20 there’s a mag­nitude –1 flare west­north­w­est above a hand­span above the hori­zon. At 3.22:06am there’s a brighter mag­nitude –4 flare in the east­south­east. These will be fast; they’ll last for just a few seconds.

Flare Simulation. Source: Wikimedia Commons

Heavens Above, where I got these details from for the ISS and Iridium also has some transit times for fainter satel­lites, but the night sky is littered with satel­lites. If you see any­thing that looks star-like mov­ing across the sky over six-eight minutes then it’s quite pos­sibly a satel­lite. Some of these could be mis­taken for aero­planes. Registering on the site will enable you to print off your own star charts for ISS and satel­lite passes. If you’re on twit­ter @twisst can tell you when the ISS is passing over your loc­a­tion and send you alerts.

If you’re inter­ested in vis­it­ing Stonehenge for the sol­stice this year and want more prac­tical advice, like remem­ber­ing to pack toi­let roll, you’ll find Heritage Key help­ful. And if there are clouds, it might not all be bad news.

Planets and Anomalies in the Antikythera Mechanism


This post was chosen as an Editor's Selection for ResearchBlogging.orgMathematicians have a concept, Omega, that is defined as some­thing so huge that any attempt to define it actu­ally defines some­thing smal­ler. In a sim­ilar vein I reckon that any attempt to describe the ingenu­ity of the Antikythera Mechanism actu­ally ends up describ­ing some­thing less ingeni­ous instead. More research on the device has been pub­lished recently in the Journal for the History of Astronomy. I real­ise that people might be drop­ping on to this entry from a search engine, without hav­ing read any of the earlier posts, here’s a quick recap of what the mech­an­ism is.
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Astronomy in Metal Heaven


Astrolabes at the Museum for the History of Science at Oxford.

If you ever want to embar­rass me, try to get me to enthuse about a dis­play of astro­labes. They’re the kind of thing I should love. They’re devices for show­ing what is vis­ible in the sky at any given time. They’re very sim­ilar to the plan­i­spheres that people use today. The math­em­at­ics behind them is eleg­ant. The best also tend to have extraordin­ar­ily ornate metal­work to com­ple­ment the soph­ist­ic­a­tion of the devices. Yet, when they’re hanging up like this, they leave me cold.

I think the reason is that an astro­labe on dis­play is a dead astro­labe. There are bet­ter ways to show a static night sky. What you need is an astro­labe in motion to appre­ci­ate them. That’s what makes this talk by Tom Wujec so good. He demon­strates how you could use an astro­labe to tell the time. In his hands, an astro­labe becomes a lot more interesting.

Tom Wujec demos the 13th-century astro­labe video from TED.

It’s easy to under­es­tim­ate how much you can do if you’re will­ing to observe intently. What I also like about this talk is that Tom Wujec emphas­ises the import­ance of con­nect­ing with the night sky. You could claim accur­ate clocks have broken this con­nec­tion, but I’m not sure that’s the case. Where I live light pol­lu­tion is often so bad that I could not use an astro­labe. He’s right to point out that you can lose things with pro­gress. Ironically Global Astronomy Month with try to show how immense the uni­verse is, while arte­facts like this show that on a day-to-day basis for urban dwell­ers the vis­ible world is much smal­ler than the cos­mos of the past.

You can see many astro­labes like the one below at the Museum of the History of Science, Oxford.

A Persian Astrolabe at the Museum for the History of Science at Oxford.

A Persian Astrolabe at the Museum for the History of Science at Oxford.

Theorising Space Archaeology


The future archae­olo­gical site of Spaceport America. Photo (cc) Jared Tarbell

There’s a thought-provoking post on Space Archaeology about how you define the term Space Archaeology. I’ve gen­er­ally just thought of it as the archae­ology of remains asso­ci­ated with space­flight, but I’ve never seen the need to give the defin­i­tion any ser­i­ous thought. It’s a small enough field as it is without draw­ing up bound­ar­ies. Steve Wilson (I assume, the blog is uncred­ited) has given it more thought, and he’s come up with a much more inter­est­ing way of look­ing at it. He sees Space Archaeology as being made up from Aerospace Archaeology (the bit I was think­ing about), Xenoarchaeology (the mater­ial remains of alien civil­isa­tions) and Exoarchaeology (any mater­ial remains that are offworld).

My first reac­tion was does this add any­thing? Adding in Xenoarchaeology is awk­ward as there are no known alien arte­facts. There’s crank mater­ial of ancient astro­nauts and vari­ous forms of SETI which are anthro­po­lo­gical con­cerns and not spe­cific­ally archae­olo­gical. Adding Exoarchaeology only adds fic­tional mater­ial. Things like the archae­ology of ter­ra­form­ing would fit in this cat­egory. As it stands it only adds an archae­ology of things that don’t exist. The dia­gram also excludes Space Heritage and Space Junk, which do exist. As a defin­i­tion, I’m don’t think it helps. However as an ana­lyt­ical tool, I think it could be very clever.

I’ll start with Xenoarchaeology, because that’s the field that’s easi­est to dis­miss as barmy. What’s the evid­ence of palaeo­con­tact? There isn’t any really. But think­ing about how people do Xenoarchaeology, and what would be neces­sary to show the pres­ence of alien mater­ial on earth could be use­ful. Tools developed in this area can then be applied to ‘crash sites’ like Roswell in the dia­gram where Xenoarchaeology and Aerospace Archaeology inter­sect. You won’t learn any­thing about alien civil­isa­tions by study­ing Roswell, but you could learn about how humans react to per­ceived alien vis­it­a­tion. Such research could have helped at Carancas. Likewise a ser­i­ous study of how xenoar­chae­ology is prac­ticed could give genu­inely use­ful insights into the assump­tions in SETI programmes.

Similarly Exoarchaeology poses its own prob­lems when look­ing at inac­cess­ib­il­ity. Thinking about these issues could high­light how the archae­ology of space­flight in orbital space makes demands and chal­lenges that we simply don’t have on the ground. Thinking about it this way Space Heritage and Space Junk could straddle every zone between Exoarchaeology and Space Archaeology. It depends on whether you class the human waste mat­ter on the Moon as part of Aerospace Archaeology or not. I’d include Space Junk / Exogarbology too, because a lot of ter­restrial archae­ology is the study of junk.

While Space Archaeologists might not need bound­ar­ies, draw­ing up defin­i­tions can high­light what makes a field inter­est­ing and also throw some basic assump­tions that need ques­tion­ing. The one that both­ers me is the idea of Xenoarchaeology.

Oddly, it’s not the Xeno bit. I could be pedantic and say archae­ology is the study of the human past through mater­ial remains. Still, the stick­ing with human is a throw­back to the early nine­teenth cen­tury when Man (prefer­ably with a mous­tache and stovepipe hat) was a cre­ation apart from the anim­als. Early palaeo­lithic archae­ology, palae­on­to­logy and prim­ato­logy are sim­ilar enough that it’s look­ing more and more like an arbit­rary dis­tinc­tion about where human ends. It’s the archae­ology bit that troubles me. The study through mater­ial remains when, so far as is known, there are no known mater­ial remains of extra-terrestrial activ­ity near Earth. I think study­ing the human reac­tion to pro­posed alien inter­ven­tions is an inter­est­ing research prob­lem. We study ancient faiths, so why not study mod­ern faiths too? It’s just that archae­ology isn’t always the best way of doing it. Sometimes a bet­ter approach is anthropology.

Thinking about Space Anthropology could have two advant­ages. One is that it recog­nises the inter­est­ing work done by eth­no­graph­ers. Alice Gorman has poin­ted out that indi­gen­ous peoples have a rough enough time as it is get­ting any recog­ni­tion in their sac­ri­fices for space explor­a­tion. Taking American-style four-field anthro­po­logy as a model also points to some other inter­est­ing research top­ics. For example is there any­thing bio­anthro­po­logy could con­trib­ute, and how do bio­anthro­po­lo­gical con­cerns integ­rate with research that is already being done?

I real­ise that by now my response is a bit longer than the ori­ginal post, which was flag­ging up an idea and not inten­ded as a fully formed model of Space Archaeology. Even so I think it’s an inter­est­ing way of think­ing about what archae­olo­gists of space explor­a­tion do. I’d love to see it developed further.

Debunking Academics


Duty Calls by xkcd

I have some sym­pathy with altern­at­ive archae­olo­gists when it comes to debunk­ing. It’s com­mon to see blog­gers debunk­ing their work, but not so much other aca­dem­ics. One reason for that could be that aca­dem­ics, doing their work as a pro­fes­sional job in spe­cial­ist domains aren’t likely to make as many mis­takes as an ama­teur with a the­ory that cov­ers a couple of thou­sand years and the entire globe. But that can only be half the story. Some blog­gers don’t cri­ti­cise other aca­dem­ics at all. Wouldn’t it be a bit odd that aca­dem­ics never make any mis­takes? What should you do when they do?

A couple of months ago, I read an odd paper, we’ll call it Paper A, for reas­ons that might become clear below. Author A made a very simple and basic math­em­at­ical error. Something a bit like mix­ing up a plus and a minus sign and con­clud­ing that the Great Pyramid was a hole around 150 metres deep. It wasn’t that bad, but the author thought the con­clu­sions flew in the face of everything known about a site. Still, the math­em­at­ics were con­clus­ive, so he had to go with it. There were more errors, but basic­ally the paper was given one big shove in the wrong dir­ec­tion, and the very intel­li­gent and cre­at­ive author tried to inter­pret the evid­ence to fit the math­em­at­ical cer­tainty. It was pub­lished in Journal A. How do you debunk that?

What I’ve done is sub­mit­ted a paper of my own point­ing out the error. Rather than shred the paper to bits, I’ve shown how any­one can make the mis­take of assum­ing a math­em­at­ical cer­tainty. The example I give is an idea I had that, after sev­eral months, I worked out was a Bad Idea — even if it looked con­vin­cing. I ima­gine I’ll annoy Author A, but I’ve tried to take the sting out of the rebut­tal. It’ll get a brief men­tion here if it gets pub­lished, and I’ll be able to host it on an insti­tu­tional repos­it­ory, or pos­sibly the uned­ited ver­sion on arXiv. I decided to sub­mit the rebut­tal as a paper and not a blog post here because the claim appeared in Journal A, so that’s the appro­pri­ate venue to dis­pute it in. Because the rebut­tal is under peer-review I’m hid­ing the name and so on to keep it anonym­ous. Sadly it’s easy to keep anonym­ous because it’s not made any pub­lic splash. This is a shame. It was a clever piece of think­ing and had a sexy con­clu­sion. If it had been sound then it would have deserved a lot more pub­lic attention.

The reason I bring it up today is that I’ve read a much worse paper today. Paper A had one big mis­take and the smal­ler ones ten­ded to fol­low from that. Paper B has at least two and I sus­pect three or more BIG errors. One is that the author has renamed a site. It makes it dif­fi­cult to track back the prior work on the site, and the bib­li­o­graphy doesn’t men­tion it. I wouldn’t blame the peer-reviewer if he thought no ser­i­ous work had been done on the site before this paper. Another prob­lem is the sci­entific method used in the invest­ig­a­tion. Have you ever laid on your back and made animal shapes from the clouds? If have you have, does that make you a zoolo­gist? If you think that’s a bit of a leap, you might have trouble with this paper.

Paper B gives me a prob­lem. I wrote the rebut­tal of Paper A, because it was close to the sort of thing I do. It is fairly well sugar-coated and hope­fully any­one read­ing it won’t simply assume author A is an idiot. Paper B is fur­ther from what I do, but still around one of my fields. It’s a lot worse.

So now I’m won­der­ing if I should be writ­ing a rebut­tal of Paper B, given that my rebut­tal of author A’s work wasn’t per­sonal and Paper A was not as bad. I think I can write some­thing ori­ginal rebut­ting Paper B, but I can also forsee drag­ging myself into a series of boil­er­plate neg­at­ive papers. It’s not my idea of fun. I think I can pull a mit­ig­at­ing factor out of it, with some effort. An altern­at­ive is to stick it up as a research blog­ging post. It that won’t be read by many people who read the ori­ginal paper and it’s giv­ing away some­thing that with a little more effort could be a paper on the CV.

Perhaps I think about it a dif­fer­ent way. Author A was worth my tal­ent, because Author A had some­thing intel­li­gent to say, even if it was fun­da­ment­ally flawed. Author B in con­trast could be a waste of time. You should insert a five-minute gap here, because while I’m writ­ing this some­thing else has occurred to me. Author B might be a waste of time, but Audience B isn’t. Audience B could have some inter­est­ing people in it. Perhaps a rebut­tal, if I can get the tone right, could be a way of net­work­ing with audi­ence B.

I haven’t decided where I’m going with Paper B yet. If I do write a paper, then I’ll still put up a sum­mary of the prob­lem if there’s no OA option.

Mysteries and Discoveries of Archaeoastronomy by Giulio Magli


Note: Giulio Magli was one of the exam­iners of my thesis, so his book is hardly likely to get a bad review.

This review rounds off a tri­logy to go with Skywatchers, Shamans and Kings and People and the Sky. Like the other two books this could be said to be part of a World Archaeoastronomy approach, but Giulio Magli adds a twist. Some of this is down to the approach he’s taken to archae­oastro­nom­ical sites, but he also adds a bit more.

Magli’s approach is sim­ilar to what I would have done if I was writ­ing an intro­duc­tion to archae­oastro­nomy book. He tackles the sites around the world. So take a deep breath because in his open­ing sec­tion of twelve chapters — slightly over half the book — he cov­ers. Palaeolithic Europe, Prehistoric Britain, the temples of Malta, Egypt, Babylon, East North America with the Hopewell and Cahokia, West North America with Chaco and the Anasazi, Northern Mexico and Tenochtitlan, The rest of Mesoamerica and Palenque, The Incas, Nazca and Polynesia. That leaves massive holes where you would expect to find India, China, Korea and Japan and a lack of African mater­ial. That’s more due to the state of play in aca­demic archae­oastro­nomy at the moment than a fault of Magli. In gen­eral Africa has been greatly over­looked and there’s not a lot of integ­ra­tion between Asian astro­nomy and the rest of the world. It’s get­ting bet­ter, but it’s still under-represented com­pared to the Mayans and Prehistoric Europe.

If this had been the sum total of the book I wouldn’t be that enthu­si­astic about it. It’s not bad. It’s writ­ten from an astro­nom­ical point of view with some amus­ing digs against archae­olo­gists. If you were inter­ested in archae­oastro­nomy and approach­ing it from astro­nomy and not anthro­po­logy I’d recom­mend this over Aveni or Krupp’s book as an intro­duc­tion to the field. What really marks out the book as worth read­ing is sec­tion 2.
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