[time-nuts] Solstice at Newgrange

[Richard Moore]

> A visit to this site, which I make every day I can, and to this  
> particular page, will answer many questions and raise many more:

http://antwrp.gsfc.nasa.gov/apod/ap081220.html

Dick Moore
>
>
> ------------------------------
>
> Message: 5
> Date: Mon, 22 Dec 2008 16:19:19 +1300
> From: "Steve Rooke" <sar10538 at gmail.com>
> Subject: Re: [time-nuts] Solstice question, about 5000 years ago
> To: "Discussion of precise time and frequency measurement"
> 	<time-nuts at febo.com>
> Message-ID:
> 	<1231b6a80812211919g36e5d363k90d8ad994d99e540 at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> Michael,
>
> 2008/12/22 Michael Sokolov <msokolov at ivan.harhan.org>:
>> Bill Hawkins <bill at iaxs.net> wrote:
>>
>>> The passage grave at New Grange, Ireland, is one of those  
>>> astronomical
>>> wonders where the rising sun at winter solstice shines down a  
>>> relatively
>>> long tunnel to shine on carved stone at the far wall of a chamber.
>>>
>>> We know that solstice has the shortest day and the longest night.
>>>
>>> How'd they know that?
>>
>> I'll abstain from answering the last question, but I'm more  
>> interested
>> in a different question: from what I understand, the exact shape  
>> of the
>> analemma depends on the misalignment between the line of apses  
>> (aphelion
>> and perihelion of Earth's slightly eccentric orbit) and the solstices
>> and equinoxes defined by Earth's obliquity.  These things do  
>> change very
>> slowly over the course of millennia, don't they?  Isn't that change
>> significant enough that the correct stone alignment would be  
>> different
>> between today and 5000 y ago?  If they got it right 5000 y ago for  
>> their
>> epoch, why does it still work now?  Hasn't the analemma shifted far
>> enough to break the alignment?
>
> This is a very interesting point, of course, so this is my 2c worth:-
>
> 1) We talk about nano/pico/femto second differences here but I wonder
> just how far the analema has shifted in the 5000 years and just how
> much difference it would make physically to this location in Ireland.
> I assume the slit of light that shines through the passage is not
> microns wide and the target, similar. It may be that the change only
> makes a small physical difference and is within the accuracy
> percentage of the measuring instrument, being The Passage Grave.
>
> 2) Is it possible that any shift in the analema may be circular over
> that time and has reverted to it's position of 5000 years ago.
>
> 3) Bill said that this alignment is noted at rising sun on the winter
> solstice. Is it possible that originally the alignment was at a
> different time of the day, say, mid-day which would seem to be a
> better target to aim for.
>
> 4) Stonehenge dates from about the same time and there is a suggestion
> that this has an astronomical connection. If that is the case, it
> would also be affected by any shift in the analema but I wonder how
> much physical difference that would make considering, what appears to
> me, to be an instrument with quite a degree of accuracy latitude.
>
> 73, Steve - JAKDTTNW (yes, I got it right this time, said I was a  
> troglodyte :-)
> -- 
> Steve Rooke - ZL3TUV & G8KVD
> Omnium finis imminet
>
> ------------------------------
>
> Message: 8
> Date: Sun, 21 Dec 2008 19:38:11 -0800
> From: Brooke Clarke <brooke at pacific.net>
> Subject: Re: [time-nuts] Solstice question, about 5000 years ago
> To: Discussion of precise time and frequency measurement
> 	<time-nuts at febo.com>
> Message-ID: <494F0BA3.9020003 at pacific.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Hi:
>
> Isn't it the case that if the tilt of the Earth's spin axis is the  
> same now as
> it was 5,000 years ago that the Sun will shine through the tunnel  
> at the
> Solstice independent of any time or calender changes between then  
> and now.
>
> If, the tilt axis has changed then all bets are off.
>
>
> Have Fun,
>
> Brooke Clarke
> http://www.prc68.com
>
> Steve Rooke wrote:
>> Michael,
>>
>> 2008/12/22 Michael Sokolov <msokolov at ivan.harhan.org>:
>>> Bill Hawkins <bill at iaxs.net> wrote:
>>>
>>>> The passage grave at New Grange, Ireland, is one of those  
>>>> astronomical
>>>> wonders where the rising sun at winter solstice shines down a  
>>>> relatively
>>>> long tunnel to shine on carved stone at the far wall of a chamber.
>>>>
>>>> We know that solstice has the shortest day and the longest night.
>>>>
>>>> How'd they know that?
>>> I'll abstain from answering the last question, but I'm more  
>>> interested
>>> in a different question: from what I understand, the exact shape  
>>> of the
>>> analemma depends on the misalignment between the line of apses  
>>> (aphelion
>>> and perihelion of Earth's slightly eccentric orbit) and the  
>>> solstices
>>> and equinoxes defined by Earth's obliquity.  These things do  
>>> change very
>>> slowly over the course of millennia, don't they?  Isn't that change
>>> significant enough that the correct stone alignment would be  
>>> different
>>> between today and 5000 y ago?  If they got it right 5000 y ago  
>>> for their
>>> epoch, why does it still work now?  Hasn't the analemma shifted far
>>> enough to break the alignment?
>>
>> This is a very interesting point, of course, so this is my 2c worth:-
>>
>> 1) We talk about nano/pico/femto second differences here but I wonder
>> just how far the analema has shifted in the 5000 years and just how
>> much difference it would make physically to this location in Ireland.
>> I assume the slit of light that shines through the passage is not
>> microns wide and the target, similar. It may be that the change only
>> makes a small physical difference and is within the accuracy
>> percentage of the measuring instrument, being The Passage Grave.
>>
>> 2) Is it possible that any shift in the analema may be circular over
>> that time and has reverted to it's position of 5000 years ago.
>>
>> 3) Bill said that this alignment is noted at rising sun on the winter
>> solstice. Is it possible that originally the alignment was at a
>> different time of the day, say, mid-day which would seem to be a
>> better target to aim for.
>>
>> 4) Stonehenge dates from about the same time and there is a  
>> suggestion
>> that this has an astronomical connection. If that is the case, it
>> would also be affected by any shift in the analema but I wonder how
>> much physical difference that would make considering, what appears to
>> me, to be an instrument with quite a degree of accuracy latitude.
>>
>> 73, Steve - JAKDTTNW (yes, I got it right this time, said I was a  
>> troglodyte :-)