Re: Number of days since 1/1/0001
Re: Number of days since 1/1/0001
- Subject: Re: Number of days since 1/1/0001
- From: Gnarlodious <email@hidden>
- Date: Sun, 25 Nov 2001 12:05:01 -0700
Eureka!
That explains why early planetary ephemerides always listed the Julian Day
as JD.5, the noon standard. Always wondered about that!
Entity John W Baxter spoke thus:
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At 18:13 -0800 11/23/2001, John W Baxter wrote:
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> at least as
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> recently as 1912 (Russia)
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I believe Michelle is correct in saying 1917. Sorry.
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This thread reminds me that the good people of San Diego found out in the
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late 1980s that their annual celebration of the arrival of the first US
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Navy vessel in San Diego Bay was being held on the "wrong" day (at least in
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some sense). Why? Because they were celebrating according to the date
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recorded in the ship's log, and the US Navy at the time the ship arrived
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was still following the nautical method of changing the date at noon rather
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than midnight, and the ship anchored around mid-afternoon.
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So as viewed from shore, the ship's log said the ship anchored the next day.
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Why change the date at noon? Because, until the chronometer appeared, noon
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was measurable at sea and midnight was not. (Accepting local apparent
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noon...maximum sun elevation...as "noon".) 24 turnings of the half-hour
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sand-glass make for a less accurate measure of midnight than the sextant
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work does of noon.
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One more thing to look out for when dealing with dates in the records and
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literature of the past.
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--John (who misses the good old days...'Belay that tell application
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"Finder" block!')
Rachel
http://www.gnarlodious.com