> 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" <[email protected]> > Subject: Re: [time-nuts] Solstice question, about 5000 years ago > To: "Discussion of precise time and frequency measurement" > <[email protected]> > Message-ID: > <[email protected]> > Content-Type: text/plain; charset=ISO-8859-1 > > Michael, > > 2008/12/22 Michael Sokolov <[email protected]>: >> Bill Hawkins <[email protected]> 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 <[email protected]> > Subject: Re: [time-nuts] Solstice question, about 5000 years ago > To: Discussion of precise time and frequency measurement > <[email protected]> > Message-ID: <[email protected]> > 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 <[email protected]>: >>> Bill Hawkins <[email protected]> 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 :-) _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
