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Another meaning for zenith given by the Oxford English Dictionary
(http://www.askoxford.com/concise_oed/zenith?view=uk) is "the highest
point in the sky reached by a given celestial object."  This is an
additional meaning to the point directly overhead.  However, both the
Wikipedia and Encyclopedia Britannica mention only the point directly
overhead.  It would appear the scientific usage is restricted to the
point directly overhead.

On Jul 23, 2007, at 7:02 PM, George Huxtable wrote:

>
> Referring to the Wikipedia entry which read-
>
> "[edit] Theory
> If there are two people, one at Greenwich and one 15 degrees West,
> the time
> by the sun will be one hour later at 15 degrees West. So, if the
> person
> observes the position of the moon at Greenwich at noon and another
> person
> observes the moon 15 degrees west of Greenwich at their locally
> determined
> noon, then due to the one hour difference, although the sun is at its
> zenith, the moon would have moved approximately its own diameter
> across the
> sky."
>
> Fred Hebard wrote-
>
> | I read that to mean they are determining the time of local apparent
> | noon, and that it will be one hour later 15 degrees west.
>
> Well, the time of local apparent noon is always noon.

The GMT time, or even some other mean time.

>
> =================
>
> | Would you or Frank expand on what was wrong with the use of the word
> | zenith?
>
> Fred's question is easy to answer.
>
> The zenith is the point that's directly overhead to the observer.
> But (on a
> particular day), there's only one latitude at which the Sun passes
> overhead.
>
> What the Wikipedia entry is referring to is the time when the Sun
> reaches
> its highest point, which will not in general be overhead, at the
> zenith, but
> somewhat lower.
>
> However, we can all guess what he really means.
>
> George.
>
> contact George Huxtable at george@huxtable.u-net.com
> or at +44 1865 820222 (from UK, 01865 820222)
> or at 1 Sandy Lane, Southmoor, Abingdon, Oxon OX13 5HX, UK.
>
>
> >



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