Theorising Space Archaeology

Alun Science, The Past 1 Comment , , , , , ,

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.

Monkey business on Mars reveals something nifty

Alun Politics, Science No Comments , , ,

I went to Skep­tics in the Pub last week at Not­ting­ham to hear a talk by Doug Ellison on the explor­a­tion of Mars. One of the sub­jects that came up was the Gor­illa. The Sun recently repor­ted that a Mars rover had found evid­ence of a Sil­ver­back gor­illa while ram­bling across the dusty and arid plains of Mars. ‘Enthu­si­ast Nigel Cooper — who has stud­ied thou­sands of pho­tos taken by Nasa rovers and pos­ted online — said: “It’s def­in­itely a creature of some sort.“‘

I’m rub­bish at debunk­ing this kind of thing. Basic­ally I get as far as a lack of bana­nas and rain forest before yawn­ing. If someone ser­i­ously thinks that the gov­ern­ments of the world are con­spir­ing to hide the exist­ence of a lone, and pre­sum­ably very hungry, gor­illa then they have more urgent prob­lems than a lack of basic bio­logy or geo­logy. What is it that makes a global con­spir­acy to hide evid­ence of an advanced civil­isa­tion on Mars, with pyr­am­ids, faces and anom­al­ous gor­il­las plaus­ible? Unam­bigu­ous evid­ence of life on Mars would be a key to the vaults of any gov­ern­ment with a space pro­gramme, so why would sci­ent­ists hide that? You’re not going to answer that ques­tion by con­firm­ing that what we have is a rock. Still, that’s what Doug Ellison did with the video below. What makes it worth watch­ing isn’t the con­clu­sion but how he got there.

The tool he used in the video is the Mid­night Mars Browser, which you can down­load on Win­dows or Mac for free. I didn’t know about this. It’s a tool that takes the pho­tos from Spirit and Oppor­tun­ity and dis­plays them as vir­tual pan­or­a­mas. You can fol­low in the tracks of your favour­ite rover. The gor­illa might be dull, it’s a rock, but the tool for examin­ing it looks bril­liant. This is why the talk was so com­pel­ling. There’s masses of inform­a­tion about Mars you can access. You can even fol­low the (delayed) blog of a Mars rover driver at Mars and Me if you want the back­seat driver experience.

It’s an example of debunk­ing done well. I doubt that he’ll have con­ver­ted any die-hards, because simply examin­ing the evid­ence isn’t going to address their under­ly­ing prob­lems. For every­one else he’s not only shown that it’s a not a gor­illa, he’s also shown the way to more inter­est­ing places that can take our under­stand­ing of Mars fur­ther. The rest of the talk showed sim­ilar insights into the equip­ment on Mars and how you can use the data com­ing from there. As for the rest of the solar sys­tem, he runs a forum where you can find out more at unmannedspaceflight.com.

It’s not just Jack who names the planets

Alun Politics, Science 2 Comments ,

Gliese 667c. Connected to, but definitely not, Ganymede in Lyra's naming system. Photo (c) Nasa.

An artist’s impres­sion of Gliese 667c. Con­nec­ted to, but def­in­itely not, Ganymede in Lyra’s nam­ing sys­tem. Photo © Nasa.

Wladi­mir Lyra’s fol­low­ing in the foot­steps of Jack in his arXiv paper Nam­ing the extra­solar plan­ets. Cur­rently plan­ets are tagged after their par­ent star, so if we found a planet around α Ceti, it would be called α Ceti b. The b in lower case is used for the first planet to be found, c for the second and so on. a is not used to avoid con­fus­ing a planet with a star. Unfor­tu­nately in the case of some double stars a cap­ital B would be used for the second star, so names could get con­fus­ing. So why not name the plan­ets? Lyra gives a couple of reas­ons why he thinks this would be a good idea. One is that names like Bac­chus are more beau­ti­ful than names like HD 128311. One person’s beauty is another person’s mess, so I’m not con­vinced by this. How­ever, he also pro­poses that names for extra­solar plan­ets aren’t just dec­or­at­ive, there’s also the Coper­nican prin­ciple.

“Mer­cury — Venus — Earth — Mars is a sequence of equals. Sol b — Sol c — Earth — Sol d would impli­citly imply that the Earth is spe­cial in some way.” For this reason, Lyra argues that nam­ing the extra­solar plan­ets is neces­sary to avoid the impres­sion that the Solar sys­tem is spe­cial. I’m more per­suaded by this, but it misses an obvi­ous point — the Solar sys­tem is spe­cial. It’s where I am, it’s where all humans are and it’s where they’ll be for the fore­see­able future.

My biggest objec­tion to his paper was that I’m not sure how help­ful it would be. Even deal­ing with ancient his­tor­i­ans I tend to avoid clas­sical names for stars, except in a few cases. Vin­demi­at­rix or Protry­getor, names for the same star in Latin or Greek aren’t as help­ful as ε Vir­ginis, because ε Vir­ginis gives the reader a clue as to where in the sky they’ll find the star. Sim­il­arly I can see why Lyra would give the name Bellero­phon to a planet, but I wouldn’t find it as help­ful as 51 Pegasi b. The IAU have said there are likely to be too many extra-solar plan­ets to name. The prob­lem isn’t likely to be the sup­ply of names, which is a shame as Lyra solves that neatly. It’s mem­or­ising what goes where.

For that reason I’d prefer a Bayer style sys­tem so in the ε Erid­ani sys­tem you could num­ber the plan­ets from inner­most orbit to outer I, II, III and so on. It sounds simple, but it won’t work. The first star you find in a sys­tem is likely to be the most massive, not the closest to the star. Using this sys­tem you wouldn’t be able to num­ber plan­ets until you dis­covered every planet in the sys­tem. Every time you dis­covered a new planet you’d have to renum­ber the sys­tem, caus­ing havoc when you try and use older papers for com­par­ison which use a dif­fer­ent num­ber­ing, or else have a data­base of each system’s num­ber order for plan­ets. Another solu­tion would be to num­ber plan­ets in order of mass, but that’s not likely to be fool-proof either.

Another pos­sib­il­ity would be a Bayer style des­ig­na­tion which embed­ded inform­a­tion about a planet in its name. So Gliese 876 d would be Gliese 876 p1.9379, p for planet and the num­ber fol­low­ing it is the orbital period. This too has flaws though as orbital peri­ods can be cal­cu­lated from assumed masses and may be revised in the future. A pos­sible solu­tion would be to only give names to the min­imum num­ber of sig­ni­fic­ant fig­ures neces­sary. In the Gliese 876 sys­tem that would give plan­ets names p60 for b, p30 for c and p2 for d. The exact fig­ures may change, but the rel­at­ive order of peri­ods would mean you would have a fair chance of identi­fy­ing a planet named in a early paper on the sys­tem at some time in the future.

Things do change and cata­strophes occur upset­ting sys­tems. Hybrid names like 55 Can­cri p 5000 Argive might help track ref­er­ences to 55 Can­cri d as papers accrue over the years. I’ll cheer­fully con­cede a name like Althaea for planet 16 Cygni Bb (the first star dis­covered orbit­ing 16 Cygni B, hence the Bb) would be easier to under­stand. Ulti­mately though I think the prob­lem is not the names, or their alloc­a­tion. It’s what the names are used for.

The vis­ible plan­ets had names because they were vis­ible, dis­tinct­ive and needed names. Uranus and Nep­tune also got names because there were so few plan­ets so more names were not men­tally tax­ing. Lyra points out that aster­oids have names. This is true, but when 1 Ceres and 2 Pal­las were dis­covered it wasn’t anti­cip­ated that 2309 Mr Spock would be join­ing them. These days a cata­logue num­ber is essen­tial to identify an aster­oid, the name is not so import­ant. The same can be said of comets. Ori­gin­ally they were named by the date they appeared. After the dis­cov­ery of the peri­od­icity of comets by Hal­ley, they began to be named, but these days comets also bear cata­logue num­bers. So who will use these planet names?

Ontic dump:

A name for some­thing that car­ries inform­a­tion about it. e.g. An example Stew­art and Cohen give is if you know what an arrow and a head are, you can work out what an arrow­head is, even if you haven’t come across that word before.

For the vast major­ity of the extra­solar plan­ets their exist­ence will only be noted by astro­nomers, much like stars and galax­ies today. While names may be beau­ti­ful, astro­nomers don’t seem to use them for stars, nore for many galax­ies. Like­wise names may add some­thing of value to extra­solar plan­ets, but equally use of them on a reg­u­lar basis could be cum­ber­some. Names have most value where things are not eas­ily cat­egor­ised, like the rocks on Mars. Myth­o­lo­gical names have the fur­ther dis­ad­vant­age in that they are purely abstract rather than ontic dumps. An ontic dump would have the double use of not only labelling a planet, but giv­ing some inform­a­tion about it. Bayer clas­si­fic­a­tions, when used as names, are usu­ally ontic dumps, as are the cur­rent extra­solar planet names. This mat­ters in the Lyra name sys­tem as some of the names actu­ally run counter to Graeco-Roman cosmology.

As an example the name Dike is asso­ci­ated with a planet found in Libra. In clas­sical myth­o­logy Dike, Justice, is in fact an aspect of Virgo. Libra was ori­gin­ally the Claws of Scor­pio. Once the method is explained then the Lyra sys­tem makes sense, but it would be counter-intuitive in some cases for any­one with a know­ledge of clas­sical myth­o­logy. Another example would be that Amphitrite, the nymph wooed by Pos­eidon with the aid of Del­phinus is not asso­ci­ated with con­stel­la­tion Del­phinus. If names are to be used then a method divorced from the myth­o­lo­gic­ally laden mean­ings of the mod­ern con­stel­la­tions might pre­vent con­fu­sion. That’s why I think Stuart’s sug­ges­tion to use names from all sorts of lit­er­at­ure has a lot of merit. Though there’s some­thing to be said for Exoplanetology’s sug­ges­tion too.

Ulti­mately the names for the extra­solar plan­ets will be names that have mean­ing to the com­munity of reg­u­lar users. In the past clas­sical ref­er­ences were com­mon cul­ture shared by aca­dem­ics in all European uni­ver­sit­ies. Those days have gone. I could bemoan the decline in clas­sics, after all I’m an ancient his­tor­ian. But there’s also a lot to cel­eb­rate about the cre­ation of aca­demic links out­side the Euro-American com­munity. If names are adop­ted hope­fully they’ll reflect that it’s not just the num­ber of worlds that has grown, but also the astro­nom­ical com­munity from a small élite at the start of the 20th cen­tury to the world­wide exchange of inform­a­tion and ideas that we have today.

If you’re won­der­ing who Jack is, there a video on You­Tube.

The Antikythera Mechanism: Art or Science?

Alun Featured, Science, The Past 10 Comments , , , , , , , , ,

The Antikythera Mechanism. Photo (cc) Tilemahos Efthimiadis.

The Anti­kythera Mech­an­ism. Photo (cc) Tilema­hos Efthimi­adis.

This post was chosen as an Editor's Selection for ResearchBlogging.orgSome posts take quite a while to write. This is a response to Candy Minx and Mar­tin Rundk­v­ist who were dis­cuss­ing the Anti­kythera Mech­an­ism back in 2006 (Anti­kythera, Time, A Reply to the Minx). Candy Minx thought that the Anti­kythera Mech­an­ism was an expres­sion of what was already known and embed­ded in a soci­ety through things like myth and ritual. Mar­tin thought that the mech­an­ism was far more com­plex, indeed need­lessly com­plex, for an ancient soci­ety and so was some­thing quite dif­fer­ent to the folk astro­nomy of the time. Ori­gin­ally I planned to write a fence-sitting com­prom­ise. I thought that Candy Minx was right to an extent, there was no need for a device like this because rituals and folk obser­va­tion could allow people to time the year as well as they needed. At the same time I thought that Mar­tin was right to point out that the mech­an­ism gave res­ults with far more accur­acy than folk astro­nomy needed, or would even recog­nise. A dif­fer­ent sort of astro­nomy is vis­ible in the Anti­kythera Mech­an­ism. I didn’t blog too much about the 2006 paper because I atten­ded a few of Mike Edmunds’ talks on the topic and heard that more would be pub­lished, which happened in 2008. Any­how in my own fluffy and fence-sitting way I’ll now offer my compromise.

Someone with an extraordin­ary ima­gin­a­tion built the Anti­kythera Mech­an­ism and, if he were alive today, we wouldn’t hes­it­ate to call him a sci­ent­ist. I don’t know if the designer was in the same league as New­ton or Galileo, but he was cer­tainly the equal of Kepler, Coper­ni­cus or Brahe. It’s hard to over­state how extraordin­ary the device described in the 2006 paper is, but I’m going to give it a go.

If you’re the one per­son who hasn’t heard of the Anti­kythera Mech­an­ism then Nature have a handy video introduction.

All that remains now is a col­lec­tion of cor­roded lumps found off the island of Anti­kythera. The 2006 paper described what the team dis­covered after x-raying the lumps to read the hid­den inscrip­tions without priz­ing apart the device and dam­aging it. Prior to this paper it was thought that the device could keep track of the Sun and the Moon. This is no small feat.

Epicycle et deferent. Image by Dhenry @ Wikimedia Commons.
Epi­cycle et defer­ent. Image by

The Sun would be mov­ing slowly against the back­ground stars, so over the course of a year it would pass through all the signs of the zodiac. The Moon how­ever is more com­plex. The Moon also moves in front of the back­ground stars, but it only takes about 27 days to do this. It’s called the sider­eal period. So you need a couple of gears to drive those two motions. But you wouldn’t really think of the sider­eal period as a month. For most people the syn­odic period, the time between one New Moon and the next or the time between one Full Moon and the next, is a month. This is around 29½ days. Throw in extra gears for driv­ing other dis­plays show­ing eclipse cycles and it’s clearly a com­plex device. The ori­ginal stud­ies found evid­ence of epi­cycles, gears moun­ted on other gears. Add other fea­tures like dis­plays for eclipse and lunar cycles on the back and it’s obvi­ous you have a com­plic­ated device. The 2006 research showed that in fact it was all a bit more com­plic­ated than that.

The Moon’s move­ment isn’t con­stant. It speeds up and slows down. This is because its orbit isn’t exactly cir­cu­lar. Instead it’s slightly egg-shaped. The point fur­thest from the earth is the apo­gee and the point closest to the Earth is the peri­gee. When it’s near the apo­gee it travels slowly, but when it moves closer to the Earth it picks up speed until it passes peri­gee and then it slows down again. This is called the first lunar anom­aly. The dif­fer­ence is notice­able by the naked eye, if you’re will­ing to make sys­tem­atic obser­va­tions. This is all simply explained by Kepler’s Laws of Plan­et­ary Motion. There’s small prob­lem. Kepler used ellipses.

You can’t use ellipt­ical gears. The point of gears is that they must have inter­mesh­ing teeth. An ellipt­ical gear would lose con­tact with the driv­ing gear as its axis changed. Instead it seems that the mech­an­ism used two gears, one slightly off-axis from the other. The rota­tion was con­nec­ted by a pin-and-slot arrange­ment, so that the one gear wouldn’t turn at quite the same rate as the other gear. The on-axis gear can then be turned reli­ably by the drive gears, while the motion of the moon can driven by the off-axis gear. So you have a device that can track the sider­eal, syn­odic and anom­al­istic months, all while the Earth is spin­ning round the Sun. If that’s caus­ing your head to spin you might want to skip the next paragraph.

There’s another prob­lem. The lunar anom­aly describes the Moon’s travel from one apo­gee to the next. This apo­gee is also rotat­ing around the earth. If the apo­gee is in Aries then two and a bit years later it will be in Can­cer, and another two and a bit years to move into Libra until it too has trav­elled through the zodiac over about nine years. So now we have a device which tracks the Moon around the Earth, and its phases and it’s vari­able speed and vari­ations in that vari­ab­il­ity, while also keep­ing track of the Sun’s pos­i­tion, poten­tial lunar and solar eclipses and inter­cal­a­tion cycles so you know when to stick an extra month in to keep the lunar months in step with the solar year round gears, some moun­ted slightly off axis to cre­ate a pseudo-sinusoidal vari­ation using cir­cu­lar gears to replace ellipses. If you have funny feel­ing near the back of your head right now, that’s prob­ably your brain try­ing to crawl out of your ears. The Anti­kythera Mech­an­ism is insanely com­plex. Still just because it’s insanely com­plex, that doesn’t make it sci­entific.

In fact you can argue about whether or not Sci­ence exis­ted in the ancient world. Cer­tainly a lot of ele­ments like test­ing ideas with exper­i­ments didn’t really become pop­u­lar till after Galileo. On the other hand some nat­ural philo­sophy of the time was based on obser­va­tion. There was cer­tainly tech­no­logy which was the res­ult of applied know­ledge. With those kind of pro­visos a lot of ancient his­tor­i­ans would be happy with the idea of ancient sci­ence, albeit a sci­ence dif­fer­ent to post-Renaissance sci­ence. In this case, the sheer intense obser­va­tion and cal­cu­la­tion involved in mak­ing the Anti­kythera Mech­an­ism marks it out as a work of ancient sci­ence. There’s also another factor which might make it more sci­entific than artistic.

To some extent the Anti­kythera Mech­an­ism Research Pro­ject have been inter­ested in hanging a name on the device. It was thought to have ori­gin­ated in Rhodes and sunk on its way to Rome, which would have con­nec­ted it to the home city of Hip­par­chus, one of the great astro­nomers of antiquity. The 2008 paper has examined the parapegma on the mech­an­ism and dis­covered it may be con­nec­ted to Syra­cuse, home of Archimedes.

A parapegma is a cal­en­dar, usu­ally with holes for stick­ing a peg into for mark­ing the days. In the case of ancient Greece they’re inter­est­ing when they tell you what day of the month it is, because each Greek city had its own set of months. The months were usu­ally named after reli­gious fest­ivals, and this was tied into local polit­ics. That meant hav­ing your own cal­en­dar was a good way of show­ing your inde­pend­ence. The best match for the months men­tioned on the mech­an­ism is Taur­omenion, mod­ern Taorm­ina, in Sicily. This is likely to have shared some months with Syra­cuse as it was re-settled from there in the fourth-century BC, so Syra­cuse is a strong pos­sib­il­ity for the home of this device. Archimedes is said to have inven­ted a plan­et­arium accord­ing to Cicero and is thought to have writ­ten a lost book on astro­nom­ical devices. How­ever he could not have made this device. Archimedes died in 212 BC. The Anti­kythera Mech­an­ism is cur­rently thought to date to the second half of the second cen­tury BC, but that might change. But it was very likely to have been made after Archimedes death and that’s what makes it scientific.

Art can be col­lab­or­at­ive, or it can be per­sonal. Sci­ence in con­trast is built on cumu­lat­ive know­ledge. The per­son who inven­ted the gear­ing did not have to be the per­son who made the astro­nom­ical obser­va­tions. He didn’t even need to live in the same cen­tury as the astro­nomer. In fact the maker of this device might not have done either. He could have fol­lowed a kit and added his own per­sonal touches on the cas­ing. There’s a core to this device which, once expressed, is inde­pend­ent of per­sonal vis­ion. Archimedes didn’t have his own per­sonal Moon which moved in a dif­fer­ent way to every­one else’s, while an artist can have a per­sonal inter­pret­a­tion of the Moon.

A reason people might think the Anti­kythera Mech­an­ism is a work of art is that it’s clearly the res­ult of a lot of ima­gin­a­tion. Great art requires ima­gin­a­tion, but so too does great sci­ence. It requires the kind of ima­gin­a­tion that can look at a tool­box full of circles and see ellipses. The kind of ima­gin­a­tion that can watch wheels turn within wheels as bod­ies waltz to the music of the celes­tial spheres. Another com­mon factor between art and sci­ence is that great art can show a new way of look­ing at the world, and great sci­ence does this too. That’s why I dis­agree with Candy Minx when she says “Sci­ence is always play­ing catch up with the poets.” Sci­ence can reveal beauty too, as a visit to the Anti­kythera Mech­an­ism Research Group’s homepage would show.

Freeth, T., Bit­sa­kis, Y., Mous­sas, X., Seirada­kis, J., Tse­li­kas, A., Mangou, H., Zafeir­o­poulou, M., Had­land, R., Bate, D., Ram­sey, A., Allen, M., Craw­ley, A., Hockley, P., Malzbender, T., Gelb, D., Ambrisco, W., & Edmunds, M. (2006). Decod­ing the ancient Greek astro­nom­ical cal­cu­lator known as the Anti­kythera Mech­an­ism Nature, 444 (7119), 587–591 DOI: 10.1038/nature05357

Freeth, T., Jones, A., Steele, J., & Bit­sa­kis, Y. (2008). Cal­en­dars with Olympiad dis­play and eclipse pre­dic­tion on the Anti­kythera Mech­an­ism Nature, 454 (7204), 614–617 DOI: 10.1038/nature07130

Astronomy and the Oracle of Delphi

Alun Featured, Science, The Past No Comments , , , , , , ,

This is (what I hope is) the final ver­sion of the Delphi present­a­tion. It briefly cov­ers the ground that formed the basis for Know­ing when to con­sult the oracle at Delphi. There’s more unpub­lished mater­ial, but rather than try­ing to pro­duce Delphi II, I’m going to make it part of the forth­com­ing Calendrical Cal­ib­ra­tion paper.

People and the Sky by Anthony Aveni

Alun Science, The Past , , , ,

peopleandthesky

It’s a com­mon gripe that archae­olo­gists don’t have much interest in pub­lic archae­ology. I’m not con­vinced it’s true and it’s cer­tainly not true of archae­oastro­nomy. People and the Sky is Anthony Aveni’s latest (ori­ginal) book. He’s the most pro­lific of the pop­u­lar archae­oastro­nomy authors, so it’s no sur­prise his prose is pretty well pol­ished. I like this book, and if you don’t have any by him it’s well worth buy­ing. If you’ve Stair­ways to the Stars, his earlier archae­oastro­nomy over­view then I’m not so sure.

I’ve been think­ing about whether the World Archae­oastro­nomy approach works. Anthony Aveni’s work would be an argu­ment in its favour. While he’s best known for his work in Mesoamer­ica, he’s also done ori­ginal research in the Medi­ter­ranean and the south­west­ern USA. One of the reas­ons he can do this without being trivial is that he’s inter­est­ing in how to relate astro­nomy to archae­ology and vice versa. Wherever it is you’re study­ing in the world, there’s the prob­lem of tying the global per­spect­ive of astro­nomy to archae­ology, which is always local. People and the Sky could be said to be a col­lec­tion of a dozen ways of try­ing to solve that problem.

The intro­duc­tion starts by say­ing why the sky was import­ant in the ancient world. It’s brief and rap­idly turns into a para­graph on each chapter. Any­one who’s bought the book is pre­sum­ably already sold on the idea that the sky was import­ant, so brev­ity is not an issue. The open­ing chapter The Storyteller’s Sky intro­duces the role of the sky in ancient cos­mo­lo­gies. This sec­tion is heav­ily biased to the New World, with May­ans, Aztecs and the Navajo and the Baby­lo­ni­ans from the Old World. The selec­tion reflects Aveni’s expert­ise. The next chapter, Pat­terns in the Sky, opens with a per­sonal anec­dote, but the range of sources is much greater. Here Aveni’s world archae­oastro­nomy approach works to show the diversity of pat­terns seen in the night sky. As well as the Baby­lo­ni­ans and May­ans, he also throws in many more cul­tures includ­ing the Egyp­tians, Barasana of the Amazon and the Incas. This last group is inter­est­ing because for them the pat­terns in the sky include spaces where the stars aren’t vis­ible. In the Milky Way dark neb­u­lae blot out stars, mak­ing dis­tinct­ive sil­hou­ettes which the Inca recognised.

The Sailor’s Sky des­cibes one of my favour­ite arte­facts, Poly­ne­sian stone canoes. They sound like some­thing out of the Flint­stones, but they’re bet­ter described as sim­u­lat­ors. A novice naviagator would sit by the stones look­ing out at the hori­zon learn­ing which stars rise over it. With this know­ledge he’d be able to nav­ig­ate across the vast dis­tances of the Pacific ocean. There’s some dis­cus­sion of Inuit nav­ig­a­tion, but this is mainly a Poly­ne­sian chapter.

The Hunter’s Sky includes and handy guide on how to tell the time using the Plough, assum­ing there’s no clouds over it and you’ve for­got­ten your watch. This draws on Plains Indi­ans, the G/wi of Bot­swana, the Mursi and Stone­henge. The inclu­sion of Stone­henge here is inter­est­ing. It’s a Neo­lithic monu­ment, and that’s usu­ally asso­ci­ated with farm­ing. Aveni argues that Bri­tons were semi-nomadic in this period. It’s plaus­ible, archae­olo­gical evid­ence is sug­gest­ing there was plenty of move­ment in the land­scape through to the Early Bronze Age, so sea­sonal use of mega­lithic sites would make sense.

It’s the next chapter that tackles the Farmer’s Sky. He opens by dis­cuss­ing Works and Days by Hesiod, which he dates to the ninth-century BC. That seems a bit early to me, I would have said it was writ­ten at a hun­dred years later. How­ever, I would agree that the integ­ra­tion of astro­nom­ical and eco­lo­gical imagery in the poem is import­ant and points to an extens­ive know­ledge of the sky. He uses the word ‘sys­tem­atic’ to describe the astro­nomy, but I’d be wary of say­ing there was a sys­tem as such. He moves on to Rujm el-Hiri, a site which I haven’t read much about after hear­ing it called “the Stone­henge of the Levant”. If I hear any­thing is called “the Stone­henge of any­where that isn’t Stone­henge” then I become wary. Thank­fully Aveni’s explan­a­tion isn’t an attempt to shoe­horn a Stone­henge model onto a site, but I’ll have to read the rel­ev­ant art­icles before I’m con­vinced of some of the claims. He also describes Indone­sian rice farm­ing using bam­boo as a sight­ing tool, which was entirely new to me.

The later chapters move more towards ideo­logy. The House, the Fam­ily and the Sky is about the organ­isa­tion of domestic space, based on cos­mo­lo­gical prin­ciples. The Navajo, Pawnee and the vari­ous tribes of the Orinoco make up much of this chapter but he also men­tions the Batammaliba of Benin and Togo and Gil­bert Islanders, before mov­ing back the the Amer­icas with the Inca. This may be one of the big­ger growth areas in archae­oastro­nomy in the com­ing dec­ades as it deals with the kind of things people do without think­ing. This con­nects the sky with ter­restrial order.

This is expan­ded on in The City and the Sky. The Mayan city of Teoti­huacan makes an appear­ance, not sur­pris­ingly as Aveni has done a lot of work on pecked cross circles there. He’s also looked at the Etruscan basis for town plan­ning, and this can be found here too. He also talks about another obvi­ous example of celes­tial plan­ning, Beijing, and the astro­nom­ical records of the Chin Shu dyn­asty (3rd cen­tury AD). This use of power leads neatly onto The Ruler’s Sky. The Pow­hatan attacks on Vir­ginia led by Opechan­canough add an inter­est­ing altern­at­ive view­point to the Mayan and Baby­lo­nian uses of astro­nomy and astro­logy else­where in the chapter. China and Babylon form the basis of the fol­low­ing chapter The Astrologer’s Sky, though there is also a dis­cus­sion of Chey­enne sham­an­ism and a blink-and-you’ll-miss-it men­tion of India.

The Timekeeper’s Sky con­cen­trates on just two cul­tures, the Romans and the May­ans. I don’t know whether to be pleased or dis­ap­poin­ted about that. I find the Greek cal­en­dar cheer­fully chaotic and worth look­ing at in its own right. On the other hand I’m will­ing to bet that if Aveni had done that, he would have come across some of the same curi­os­it­ies I have. So while I’d say there’s a gap here, it’s not one I’m actu­ally com­plain­ing about. To some extent this chapter cov­ers sim­ilar mater­ial to the earlier hunt­ing and farm­ing chapters.

The final chapter of the book is The West­ern Sky. It’s a slightly dif­fer­ent chapter to the oth­ers. It asks an obvi­ous ques­tion. Given the exist­ence of so many astro­nom­ies, why has one come to dom­in­ate sci­ence? This why ques­tion is re-visited in the Epi­logue which Aveni uses to reit­er­ate that for many people Astro­nomy had been some­thing very dif­fer­ent both in meth­ods and aims to the mod­ern sci­ence it is day.

As a whole, the book shows some of the lim­it­a­tions of a world archae­oastro­nomy approach. I didn’t see any­thing sub­stan­s­tial about India in the book. Ref­er­ences to China were lim­ited and there was noth­ing of Korea or Japan that I saw. To a large extent this reflects fault-lines in aca­demia. A lot of far east­ern mater­ial isn’t pub­lished in west­ern lan­guages. That’s not really true for India though. There’s some extremely good archae­ology hap­pen­ing there and a large amount of his­tor­ical mater­ial, includ­ing astro­lo­gical texts. It works for text­books intro­du­cing the sub­ject, but I am won­der­ing to what extent a World Archae­oastro­nomy approach can be used in research publications.

Com­pared with his other works, this is def­in­itely at the shal­low end but it’s not fair to dis­miss it as shal­low. Like the best intro­duct­ory texts it leads on to other mater­ial. For instance I’ll be look­ing up more about Rujm el-Hiri now. If you’re look­ing to buy a book and you have Stair­ways to the Stars, then this is one to get out of the lib­rary. If you don’t have Stair­ways to the Stars, then this would be the bet­ter book to buy.

Social Astronomy and Intentional Inaccuracy

Alun Science, The Past 1 Comment , , ,

FullMoon
Can you spot the Moon in this photo? Photo (cc) Andréia.

One of the reas­ons I’m put­ting up more stuff recently is that it’s a spin-off from pol­ish­ing the thesis. Reas­on­able ques­tions would be: What do is Social Astro­nomy? and Why is that Archae­oastro­nomy and not His­tory of Astro­nomy? The answers to both ques­tions are connected.

Social Astro­nomy is the study of astro­nomy as used for social pur­poses. This fits very neatly with Archae­oastro­nomy which these days tends also to be referred to as Cul­tural Astro­nomy. In con­trast His­tory of Astro­nomy, espe­cially in the ancient world, has ten­ded to be the story of how Astro­nomy in its mod­ern sense grew from ancient prac­tices. An example of very good His­tory of Astro­nomy in an ancient con­text would be James Evans’s book The His­tory and Prac­tice of Ancient Astro­nomy. It’s a very good book cov­er­ing the math­em­at­ical basis ancient astro­nomy and how people got pro­gress­ively more accur­ate at pre­dict­ing the move­ment of the plan­ets. I think that’s going to be a defin­ing work on ancient astro­nomy for a gen­er­a­tion, but there’s still things it misses. The quest for accur­acy is the under­ly­ing nar­rat­ive of a lot of ancient astro­nomy books. It misses the factor that people, espe­cially the ancient Greeks, might have also wanted and aimed for inac­cur­ate astro­nomy. That is an odd claim, after all isn’t astro­nomy a sci­ence?
More

Herodotus and the shape of the world

Alun Featured, Science, The Past 1 Comment , , , ,

Atmosphere

What shape did the ancient Greeks think the world was? Usu­ally the answer is to look in philo­sophy texts. It’s been sug­ges­ted that Thales thought the world was flat and floated on water. His (pos­sible) pupil, Anax­i­m­ander, thought the world was drum-shaped and that people lived on the of the flat sides. The drum, he said, floated in the centre of the uni­verse. Anaxi­menes, the next philo­sopher at Mile­tos went back to a flat earth, float­ing on air. The prob­lem was solved when Pythagoras decided the world must be round some time around the late sixth cen­tury BC. So that’s that. Or is it?

There’s a couple of prob­lems with this. One is that the writ­ten sources aren’t the philo­soph­ers them­selves. They’re later records of what other philo­soph­ers thought they said. Or what later philo­soph­ers wanted other people to think they said. There’s a ques­tion of where they got their inform­a­tion from. They cer­tainly could have had access to the ori­ginal writ­ings. That might have been dif­fi­cult for Pythagoras though, who was head of some­thing like a secret soci­ety. The best sources on Pythagoras we have are from the 3rd cen­tury AD, about a eight cen­tur­ies after he lived. There was also a habit in the ancient world of stick­ing an older philsopher’s name on your book. Like today old wis­dom was often much more respec­ted than new.

Another reason to be scep­tical is that these were philo­soph­ers. They were at the cut­ting edge of thought, which doesn’t mean that hicks in the fields would have been up-to-date with cos­mo­lo­gical thought, or believed it. For example Pythagoras’ idea of a round earth would be con­sidered dan­ger­ously mod­ern in some parts of Texas. Don “Someone has to stand up to the experts” McLeroy prefers an older text for his thought. Like­wise what would your less-educated ancient Greek think?
More

Real Astronomy is Naked

Alun Science No Comments , ,

Replica of the telesope Herschel used to see Uranus
A rep­lica of Herschel’s scope raises the ques­tion: Is it only naked-eye astro­nomy that’s real?
You can insert your own joke about being able to see Uranus.

Sky at Night Magazine have put up a ques­tion on their twit­ter account:

A reader says remote observing, with online scopes, is real astro­nomy as you con­trol everything, even though you’re not there. Do you agree?

It’s some­thing astro­nomers do from time to time, point at oth­ers and claim that’s not real astro­nomy. I remem­ber, when CCDs were start­ing to be adop­ted for astro­pho­tos, old hands would dis­par­age their digit­ally enhanced neigh­bours. For some reason a chem­ical pro­cess prone to noise and mis­takes in a hobby photo lab was more real that non-destructive manip­u­la­tion of digital data. It begs the ques­tion what do you think is real?

If there is a divide, it’s between naked eye astro­nomy and everything else rather than between one tele­scope use and another. Oth­er­wise the line is pretty arbit­rary. Are you only a real astro­nomer if you pol­ish your own mir­rors and grind your own lenses? Is it the length of cable between your tele­scope and com­puter? I’ll accept that observing via Slooh and your own tele­scope is dif­fer­ent, but it’s no less real. After all there isn’t a pro­fes­sional astro­nomer actu­ally in the Hubble tele­scope with his fin­gers on the focus, yet that doesn’t stop aca­dem­ics being real astronomers.

It depends on what it is you want to acheive when you’re doing astro­nomy. If you want to make dis­cov­er­ies, which seems pretty real to me, then tech­no­lo­gical aids help. If that’s an aid on the other side of the world, or down­load­ing inform­a­tion from ESA, then so be it. If you want to prac­tice astro­nomy in the way that most observ­ers of the sky have, then it’s naked eyes that you need. In some ways you could even say it’s more real. Astro­nomy, as far as the nam­ing of the stars went, was done by the naked eye. It’s only with a wide view that the pat­terns of the con­stel­la­tions can be seen. Des­pite that using more than your eyes is can aug­ment what we see rather than rob of us of it. Remote scopes offer a chance any­one to visit a dark sky site and see more of the uni­verse on any given night regard­less of fam­ily com­mit­ments or health issues.

I’m not sure why you’d want to draw a line though. Astro­nomy, like a lot of things, is more inter­est­ing when you can use it as a base to explore from, rather than a box to be con­fined in.

Does British investment in astronauts match the nation’s ambition?

Alun Politics, Science No Comments , , , ,

MoneyWhatMoney
The Brit­ish invest­ment in ESA’s astro­naut pro­gramme. Photo (cc) Stu­art Pil­brow.

Becom­ing an astro­naut is the pin­nacle of achieve­ment for any­one involved in space sci­ence and technology.

So, after the selec­tion of Major Time Peake as the UK’s new ESA astro­naut, how ser­i­ous are the gov­ern­ment of reach­ing the pin­nacle of acheive­ment? “No addi­tional funds would be made avail­able to help pay for the costs of Major Peake’s train­ing, Sci­ence Min­is­ter Lord Drayson said.” While the UK’s Depart­ment of Innov­a­tion, Uni­ver­sit­ies and Skills is happy to asso­ci­ate them­selves with Tim Peake’s suc­cess and say they’re invest­ing in our future, the Brit­ish invest­ment in astro­naut­ics will cur­rently remain €0.
More

1 2 3 4 5 6 7