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This is soooooo cool
Posted: 28 June 2012 05:42 AM   [ Ignore ]
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I want one!!!

And it´s a sundial.

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Posted: 30 June 2012 04:31 AM   [ Ignore ]   [ # 1 ]
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(the Posting Monster is back! It ate my original message!)

Just a note that given the very slow change in declination around Solstice, this time marker is not very accurate - it will probably display those words for a month or so centered on the Solstice. Still: cool!

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The Kruger-Dunning effect is rampant on internet fora.
J. Kruger & D. Dunning (1999), Unskilled and unaware of it: how difficulties in recognizing one’s own incompetence lead to inflated self-assessments. J Pers Soc Psychol. 77, 1121-1134

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Posted: 30 June 2012 05:07 AM   [ Ignore ]   [ # 2 ]
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Seeing the form and build of the contraption I would not be surprised if it really was quite accurate. In the sense that the word is only on one or two days precicely formed.
And the time before and after it´s not complete, cutoff letters etc.
Seems that every little nook, cranny, cutout, length and width is very calculated.
Only way to find out is to go there and hang around for while…

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“By the sweat on our brows, and the strengths of our backs…Gentlemen. Hoist the Colours! And you, madam, I warn you, I know the entire Geneva Convention by heart!”
Trust me.

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Posted: 30 June 2012 05:41 AM   [ Ignore ]   [ # 3 ]
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Unfairly Balanced - 30 June 2012 05:07 AM

Seeing the form and build of the contraption I would not be surprised if it really was quite accurate. In the sense that the word is only on one or two days precicely formed.
And the time before and after it´s not complete, cutoff letters etc.
Seems that every little nook, cranny, cutout, length and width is very calculated.
Only way to find out is to go there and hang around for while…

It is the sun itself that puts up constraints. The sun is not a point source, and the declination change around solstice is very slow.

Between June 9 and July 2nd,  a 3.5 week period, the declination change of the sun is less than the sun’s diameter (0.5 degrees).
Between June 12 and June 29, so 2.5 weeks, the declination difference is even less than half the sun’s diameter, i.e. less than the distance from solar midpoint to solar limb:


Date                       DEC sun (deg)
2012 Jun 08 12:00:00.0     + 22.90188  
2012 Jun 09 12:00:00.0     + 22.98373    
2012 Jun 10 12:00:00.0     + 23.05885    
2012 Jun 11 12:00:00.0     + 23.12718    
2012 Jun 12 12:00:00.0     + 23.18872    
2012 Jun 13 12:00:00.0     + 23.24344    
2012 Jun 14 12:00:00.0     + 23.29132    
2012 Jun 15 12:00:00.0     + 23.33234    
2012 Jun 16 12:00:00.0     + 23.36650    
2012 Jun 17 12:00:00.0     + 23.39378    
2012 Jun 18 12:00:00.0     + 23.41417    
2012 Jun 19 12:00:00.0     + 23.42768    
2012 Jun 20 12:00:00.0     + 23.43430 * Solstice  
2012 Jun 21 12:00:00.0     + 23.43403    
2012 Jun 22 12:00:00.0     + 23.42688    
2012 Jun 23 12:00:00.0     + 23.41285  
2012 Jun 24 12:00:00.0     + 23.39196    
2012 Jun 25 12:00:00.0     + 23.36420  
2012 Jun 26 12:00:00.0     + 23.32960  
2012 Jun 27 12:00:00.0     + 23.28817  
2012 Jun 28 12:00:00.0     + 23.23993  
2012 Jun 29 12:00:00.0     + 23.18491

2012 Jun 30 12:00:00.0     + 23.12314  
2012 Jul 01 12:00:00.0     + 23.05463    
2012 Jul 02 12:00:00.0     + 22.97942
2012 Jul 03 12:00:00.0     + 22.89754

During this latter 2.5-week period direct sunlight will hence always shine through the centerline alignment of those cutouts no matter how carefully they are constructed, and hence the letters will be visible. There is no way to avoid this.

And quite likely, they will be for an even longer period (up to a month or more) considering that the cut-outs have a clear diameter, allowing for slightly slanting angles of light.

It is for this reason that solar alignments such as at Stonehenge, will never be reliable and exact time-keepers, something a lot of people forget when they suggest such structures were built to exactly determine the day of Solstice, e.g. a strict practical calendrical use (rather than symbolic marker).

 

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———
The Kruger-Dunning effect is rampant on internet fora.
J. Kruger & D. Dunning (1999), Unskilled and unaware of it: how difficulties in recognizing one’s own incompetence lead to inflated self-assessments. J Pers Soc Psychol. 77, 1121-1134

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Posted: 30 June 2012 06:09 AM   [ Ignore ]   [ # 4 ]
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In that case I´m going to build a counter rotating house on the northpole.
(patent pending)

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“By the sweat on our brows, and the strengths of our backs…Gentlemen. Hoist the Colours! And you, madam, I warn you, I know the entire Geneva Convention by heart!”
Trust me.

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