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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Is the date ever the same globally?
From: Jim Thompson
Date: 2004 Oct 15, 06:37 -0300
From: Jim Thompson
Date: 2004 Oct 15, 06:37 -0300
I need to check my understanding of this with the list. Is this line from a book correct: "...at the instant of GMT 1200, the date is the same all over the world"? I think it is wrong. 1. On http://jimthompson.net/boating/CelestialNav/DatesTimeDiagrams.htm I tried last year to prove that statement to myself, but was unable to do so. See http://jimthompson.net/boating/CelestialNav/TimeDateConversionTable.htm. Note in that table (I made up this table, so I hope it is right) that when it is 1200 at Greenwich on day 10 (say), it is is 2400 the previous day in Time Zone Y (ZD -12), and so it can never be the same date at every place on the planet at once. The instant it turns to 1200 at Greenwich, the time in M is 2400 on the same day, but the time Y is 2400 on the previous day Right? 2. There are 25 time zones, not 24, right? The way I see it, that is because the 15d span of longitude around the IDL is divided into Y (ZD -12) and M (ZD +12). Although time is always the same in those two "half zones", date is always different. Am I right? Or is that just splitting hairs to say that there are 25 time zones, since the time in Y and M is always the same, even though the date is different? (I am working on a CN PowerPoint presentation for teaching, so need to pin this down.) Jim Thompson jim2@jimthompson.net www.jimthompson.net Outgoing mail scanned by Norton Antivirus -----------------------------------------