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Winter solstice sunset and sunrise
From: Jim Thompson
Date: 2003 Dec 23, 07:34 -0400
From: Jim Thompson
Date: 2003 Dec 23, 07:34 -0400
Pierre, I found this in Bowditch section 1521: "The error due to lack of uniform rate of revolution is removed by using a fictitious mean Sun. Thus, mean solar time is nearly equal to the average apparent solar time. Because the accumulated difference between these times, called the equation of time, is continually changing, the period of daylight is shifting slightly, in addition to its increase or decrease in length due to changing declination. Apparent and mean Suns seldom cross the celestial meridian at the same time. The earliest sunset (in latitudes of the United States) occurs about two weeks before the winter solstice, and the latest sunrise occurs about two weeks after winter solstice. A similar but smaller apparent discrepancy occurs at the summer solstice." Jim Thompson jim2@jimthompson.net www.jimthompson.net Outgoing mail scanned by Norton Antivirus -----------------------------------------