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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Dropping leap seconds and the impact on celestial navigation
From: Fred Hebard
Date: 2011 Sep 12, 12:36 -0400
From: Fred Hebard
Date: 2011 Sep 12, 12:36 -0400
I'm afraid I was speaking rather imprecisely, referring to noon as the meridian and 11:30 am as the time of day on a mechanical watch. On Sep 12, 2011, at 12:30 PM, Herbert Prinz wrote: > On 2011-09-12 14:18, Fred Hebard wrote: >> I was merely expressing concern at decoupling of days from the course of the sun. No tongue in cheek. >> >> >>> On 2011-09-10 16:24, Fred Hebard wrote: >>>> ... I wonder what will happen 200 years from now. Will noon be 11:30 am? That would be unacceptable to me. > > > Fred, > > Let me double check that I understand the terms correctly as you mean them in your question "Will noon be 11:30 am?" > > If the question is to be taken at face value, "meridies" then stands for the original meaning "middle of the day", as we reckon it, i.e. 12:00, regardless of what it means astronomically, (hence a.m. is any time between 00:00 and 12:00); While "noon" stands for the moment that the sun (in some sense) is passing over some meridian? > > These definitions are reasonable, but they no longer go without saying. My uncertainty is just one example how difficult the precise discussion of this topic is, given that the terminology is so fraught with history and connotations and so widely used in other fields than astronomy (geography, horology) and everyday speech. > > Herbert Prinz > > >