Thursday, 30 October 2014

Long Barrow Solar Alignments

A very quick desktop survey of my local Long Barrow alignments:  The yellow line is sunrise, orange sunset. (Definitions of what constitute the moment of sunrise or sunset vary). They are taken from the excellent Suncalc.net 

The new Long Barrow at All Cannings is designed to align to the midwinter solstitial sunrise, with the rising sun flooding the passageway with light.

Adam's Grave Dec 21st

Kitchen Barrow June 21st
 
West Kennet Sept 21st

And of course Stonehenge June 21st 
(note sunset along Great Trilithon)

Click any to enlarge - and follow link to SunCalc to play with the alignments.


20 comments:

  1. Curious how these things always seem to exist in certain formations. If you knew what the pattern was, you might be able to work out where to look for other monuments.

    Would this one be part of the "All Cannings" list?

    http://www.pastscape.org.uk/hob.aspx?hob_id=215819

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    1. Jon - Yes, but it would be hard to check now. Lots lore to look at when I have time. Cheers

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  2. When we look at the various surveys of relatively similar monuments to Long Barrows , that could be considered to have an orientation e.g. passage graves , wedge tombs ,dolmens ,long cairns , chambered cairns , allee couvertes , antas de corredor ,tombe de gigante etc the surveyors , principally Claus Clausen , Tim Phillips and most importantly Michael Hoskin who has investigated over a thousand in Europe note that whilst there are general local preferences , as well as anomalies , there is no overall preference for orientations to Thom paradigm events and the best that can be said is that the majority of orientations allow the sun to enter the passage at some time in the year with exceptions that are aligned too far north to even allow the moonlight to directly enter the passage . Calculating the potential astronomical "alignments" is easy ,appealing and with decent palns and surveys can be done distantly , but the reason for siting and subsequent orienation may have much more to do with the landscape setting rather than solstices etc .

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    1. Geo - Knowing that there are no general rule of orientation I was surprised when i looked at the three nearest to me, I knew of West Kennet and had guessed Adam's Grave from walking it. I must look at the horizon again from the Kitchen Barrow to see if it is a possible solar alignment or just following the hill.

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  3. Tim , as we don’t know the exact orientation of the passage we can only guess at it from the orientation of the barrow and that looks approx 40 degrees ,even with a flat horizon that orientation wouldn’t provide an alignment on the solstice , but as the height of the horizon provides an alt around 4 degrees it would mean that the orientation would have to be close to 60 degrees to be oriented to the solstice . The barrow does however follow the general trend of the spur on which it is built .

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  4. Long Barrows (the original prehistoric ones!) are not built to any astronomical alignments, they are built parallel to water courses. Some of these watercourses still survive (in a reduced state today) and can be easily mapped as shown on my prehistoric map series available on Amazon - showing that every Long Barrow and the associated water course in Wiltshire (and soon the South Downs).

    Although I understand the reason Tim planned the 'Newgrange effect' and congratulate him on his 'monumental' achievement - lets not get carried away with the astronomy which does have a historical connection - navigation.

    RJL

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  5. Just looked at the Suncalc - neat bit of Javascrpting but not overly accurate. Place the date back to say 100AD and it breaks ;-) - which suggests that it has not calculated the changes in solar azimuth positioning due to precession.

    RJL

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    1. "which suggests that it has not calculated the changes in solar azimuth positioning due to precession. "
      The change in the azimuth of the sun as seen from the same point is due to obliquity of the ecliptic /axial tilt .
      It is not precession .
      The rate of precession is one degree every 72 years ,it's not difficult to calculate how much that change would be in a millenium or when the monument was built . Contrast and compare the difference between the present azimuth and what it would be if it changed at that rate . This has been explained to you numerous times ,why do you persisit in repeating the error ? Constantly repeating it will never make it true . Google the rate of precession and the change in obliquity then contrast and compare with the change in the azimuth of the solstice between the present , 72 years ago , 1000 years ago and 2500 BC and hopefully you might understand , but I'm not holding my breath .

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  6. "The change in the azimuth of the sun as seen from the same point is due to obliquity of the ecliptic /axial tilt"

    And the change to the obliquity of the ecliptic is due to precession - you're just playing with words, yet again! If the earth did not wobble the sun would rise and set at the exact same spot throughout history - its not rocket science.

    Keep holding that breath!

    RJL

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  7. So you decided to dig a bigger hole for yourself .

    "And the change to the obliquity of the ecliptic is due to precession "
    Another wonderful fantasy .Do you have a clue what the terms actually mean ? As always breath will not be held on any support /data for that . Read the above or get a beginners book on astronomy ,look up precession then obliquity .

    Pointing out facts and using falsifiable data is not playing with words .
    You don't even play with words you jumble them up in a senseless melange .
    You have avoided looking at the facts for years .The data ,something that you avoid , is noted above discuss that .
    Here’s an example from two years ago of yet another attempt to make you see sense
    “Precession has had little effect on the declination of the sun at solstices /equinoxes etc over the millennia . What has changed and the term you really needed is obliquity (of the ecliptic ), which changes at approx 0.1 degrees per millennium .” If you can’t grasp this here is Clive Ruggles has to say about the subject “ The limiting annual and monthly declinations of the sun and moon are not affected by the precession of the equinoxes “ That is the basic point that you get wrong . He continues “”but they have changed noticeably over the past few millennia .This because of the gradual decease in the obliquity of the ecliptic “ . If you still don’t get it , take your time and re-read or simply provide some quote from someone reputable ,that supports your view . As always breath will not be held and the expectation is “nurse” ,name “jokes” ,unnecessary caps and childish abuse , getting further into the myre by avoiding the point and introducing a new equally errorful one, or silence .

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  8. As with all academics Sherlock you fail to comprehend the basic scientific principle of 'cause and effect'.

    I was watching an interesting programme about the delta in Egypt that had silted up in prehistory - they spent most of the programme trying to tell the poor viewer what happens during the silting process with lots of 'experts' to back-up the pointless message.

    Sadly, LIKE YOU they failed to understand that they are talking about the effect not the cause of the delta - which is the the drop in ground water over the last 5,000 years- simple to prove (as the nine pyramids of the Nile all used to be on the shorelines of the Nile, unlike now.

    You are also talking about the effect not the cause - as you admitted in the past YOU HAVE NO IDEA WHAT CAUSES THE OBLIQUITY OF THE ECLIPTIC - no surprise as you're an idiot, but even an idiot should understand that precession (the earth wobbling on its axis no less!!) will have a whole host of other consequences such as you're obliquity of the ecliptic.

    RJL

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  9. As predicted and as is always the case ,a complete lack of supporting evidence or data , and an evasion of the data and evidence provided .All that you are capable of being childishly rude .
    As has been explained to you , before nobody knows for sure what caused obliquity , however , it certainly wasn't precession , yet another term you obviously don't understand .To make such a claim is up there with your best .
    Breath not held for provision of any data or supporting evidence including any quote from a reputable authority on anything you fantasise about precession . Your only possible response is silence , bluster , name calling or some outlandish non sequitor whilst evading the data provided that will make you appear even more ignorant of the subject .
    It does however keeps us in laughs and stories that most would never believe unless actually read .
    Quite simply , provide one supporting quote for the ridiculous "And the change to the obliquity of the ecliptic is due to precession " or provide anything to refute the data I have provided . We realise that can't.

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  10. The interesting thing about the above conversation is that only one of you completely knows their stuff and the other obviously doesn't have a clue. But both of you speak with almost equal authority. Anyone new to the subject could not easily tell which is which (and nobody in the relevant community can be bothered to contribute so as to guide the casual reader on who might have something worth saying).



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    1. Actually Jon, doesn't really matter who is wrong or right as we all agree it does happen and can be a tool to help us date prehistoric monuments.

      The blog was about the 'suncalc' and Sherlock (as always) turned it into a debate about 'semantics', which seems to be commonplace in academia - hence the stagnation in subjects like archaeology,because of anonymous trolls who just wish to 'argue the toss'.

      RJL

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    2. What begins as a error in a comment soon becomes a catalogue as the originlal point is evaded and further errors are added as part of the evasion .It would make more sense to stick to one error at a time as the expotential increase leads to bigger posts .

      “The blog was about the 'suncalc'”
      The blog thread was actually about and titled “Long Barrow solar alignments “
      Which were being discussed until you entered with the nonsense about LB’S being navigational aids and the oft repeated error “solar azimuth positioning due to precession.” Which was then compounded with “And the change to the obliquity of the ecliptic is due to precession “ , both astronomical errors in magnitude and subject matter. The best you could manage, apart from the usual abuse , caps and bluster was that it doesn’t matter and it is all semantics . Even for you these are gargantuan errors and you obviously don’t understand the terminology including the latest misunderstanding and misuse of the term semantics .
      Rate of Precession = 1° in72 years . The change in Obliquity in the period from when the megalithic monument at Stonehenge was built to today is just over 0.5 degrees = decreasing at a rate of about 47" per century . The rate of Precession in that same period of build to present means a change of 62.5 degrees . The magnitude of the difference , a factor of 125 , is not semantic and that is excluding the real problems of your misunderstanding of the terminology .

      “we all agree it does happen “ But not to the extent or caused by what you believe i.e. you are out by a factor of 125 , to clarify again , 0.5 degrees not 62.5 degrees .That is not “arguing the toss” or trolling , that is something you do when you fail to acknowledge mistakes but continue to be abusive shout and make claims with no supporting data or evidence . There is also a complete lack of support from any outside parties .

      “and can be a tool to help us date prehistoric monuments.” When we have dated a monument by more reliable methods an astroarchaeological study can provide some possible additional info but it does not make sense to use it as the primary dating tool due to :
      1)In the absence of knowledge of the original intention of an alignment it does not make sense to date a building putatively aligned on a Thom paradigm event .
      2) Being unaware of the accuracy of the alignment exacerbates the problem .
      3) Even if we knew the intention ,the change in obliquity is so small compared with the likely error in accuracy that any extrapolation to build date would almost meaningless .
      Lockyer famously dated Stonehenge using astronomy , and we know how wrong he was . That case alone exemplifies the problems . Kate Spence attempted to date the pyramids using astronomy , she did have here critics but the study did not oppose 1) as the cardinal alignments were obviously intended . Neither was 3)opposed as the study was based on the background stars which ,unlike the lunar and solar Thom paradigm events , provided a basis for greater accuracy because of their movement due to precession ,a point that might help you appreciate your error if understood .
      Talking of being wrong , we are still waiting , despite many requests , for your “ complex calculation “ which dates Stonehenge . Do let us see it and we will clarify the problems for you .

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    3. (“The blog was about the 'suncalc'” The blog thread was actually about and titled “Long Barrow solar alignments “)

      There you go Jon - proof of the pudding!

      An anonymous troll wasting my time!

      RJL

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    4. Sherlock

      "but even an idiot should understand that precession (the earth wobbling on its axis no less!!) will have a whole host of other consequences such as you're obliquity of the ecliptic"

      Your 'passive reading skills' (or is it alzheimers?) have failed you once more - the clue is in part of the sentence " a whole host of other consequences such as you're obliquity of the ecliptic"

      I have never suggested the ridiculous stats you have just produced - if so quote me? or go back and re-read your mistakes on my blog that quoted true statistics:
      http://www.the-stonehenge-enigma.info/2012/12/astroarchaeology-dating-of-stonehenge.html

      Let's talk to you like a five year old (or an idiot) for clarification - I use the word 'precession' to refer to the earth wobbling on it's axis (that's the 'cause') one of the 'effects' is 'Axial precession' BUT I don't believe it is the only effect.

      I believe it also effects on what you call 'obliquity of the ecliptic' - its not the best phrase for this effect (but i'm not as anal as you, so I use it for your benefit and avoid confusion).

      Now go back and re-read the comments and lets hope the light-bulb moment happens - if not keep holding your breath as I've booked a place for you in Tim's new pad!

      RJL

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    5. “I have never suggested the ridiculous stats you have just produced - if so quote me? “

      Daisy , Of course you never suggested these stats and of course I never suggested you did . You don’t provide data , or evidence to support your beliefs .
      These are the data for precession and obliquity which you misunderstand .They are not ridiculous ,they are correct . If you don’t accept them all you have to do is provide reliable data to refute them , something you never do
      To repeat . Rate of Precession = 1° in72 years . Do you deny this ?
      The change in Obliquity in the period from when the megalithic monument at Stonehenge was built to today is just over 0.5 degrees = decreasing at a rate of about 47" per century . Do you deny this ?
      If I have made a mistake all you have to do is provide the data refuting it ,as I constantly do to refute your “beliefs “.

      “ I use the word 'precession' to refer to the earth wobbling on it's axis (that's the 'cause') one of the 'effects' is 'Axial precession' BUT I don't believe it is the only effect. “

      Precession causes axial precession ? Lol .
      A further demonstration on your total lack of understanding on the subject .

      “I believe it also effects on what you call 'obliquity of the ecliptic' - its not the best phrase for this effect .”

      Most of what you believe , or at least mention here is demonstrably wrong .
      Precession was not the cause of obliquity , again provide any reliable source supporting such a daft belief .

      You really don’t have a clue about the subject and are obviously incapable of improving that situation , but nevertheless , thank you for the unintended humour , it more than makes up for the volume of corrections .

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  11. I agree , but then I would .

    But it does highlight what you can get away with if you use bluster and shout loud enough .
    Bullying tactics work with some and most people can't be arsed dealing with the nutters, so remain silent .
    Pesonally I feel they should be confronted .

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  12. I've only just happened across this thread, and felt I might offer a little clarity.

    Change in obliquity of the ecliptic is due to the changing angle (away from vertical) of the Earth's rotational axis. Presently it is about 23.5°, it was about 24° in 2500BC. It has a period of about 41,000 years and is understood to vary between about 22° and 24.5°

    Precession is the circular movement of the point in the sky around which all stars appear to rotate, caused by the revolution of the direction of Earth's rotational axis akin to the behaviour of the axis of a spinning top or gyroscope as it slows down. It has a period of about 26,000 years.

    So the former is a "nodding" of the axis angle, the latter is a "circling" of the axis direction - two quite distinct things. Only the former has any effect on the position of sunrise/set at the solstices.

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