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tiompan wrote: Hello Marina , Steve's book just arrived , surprisingly early , looks great . Talking of West Kennet . I think I probabaly mentioned this on forum and possibly here too ."West Kennet Long barrow is aligned 85 degrees =/-1 . Construction date from recent accurate dating combined with Bayesian statistics is 3640 -3650 cal BC . On the week before equinox 3640 BC there was a full moon seen from the barrow at an orientation of 85 degrees as this coincided with a setting sun 180 degrees in opposition the moon would appear red and have a 30% chance of eclipsing that night. Furthermore Saturn and Jupiter were in conjunction with the moon that night . " Not necessarilly meaningful but worth pointing out . I think Steve's book will really encourage people to explore the wider landscape of Avebury. I particularly like the fact that it is so full of images. Everyone with an interest in the area should definitely get one. This whole business of solstice and equinox eclipses is a very interesting one George, especially when they are on the horizon, and I have looked into it quite a bit. Now that you mention it, yes I do remember you talking about this on the old Avebury forum. It turns out that there are eras of solstice/equinox eclipses which return after a certain time. I have been able to calculate the time as a result of some of the things I found out from studying the geometry of Avebury. We were in one of these eras from 2010-15 and there would have been one at the time that WKLB was built. During these eras the likelihood of solstice/equinox eclipses occurring is much higher, and among the near misses some inevitably are visible. Whether or not the eclipse on that particular date you give is actually visible or not on planetarium software from the latitude and longitude of Avebury might depend on which value for Delta T you take. Stellarium now gives you a range of options for Delta T values. I certainly was able to find a whole series of visible eclipses from that era, including an annular one which was visible in the West on a day when the sun rose at 60 degrees, and a number of solstice and equinox ones - but the delta T value you choose to use might affect whether these are visible or whether they occur below the horizon. I'll have a look at the tables of eclipses I made and see if I can find one on the date you give but I will say that even if it was a near miss it won't have been the only one likely to happen around that time. I'll have to return to this subject later though - because I'm supposed to be packing to go to Luguvallium(!) Reply | with quote | Posted by MG 19th May 2016ce 13:18 In reply to: Re: The Geometry of Avebury (tiompan) |
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