[time-nuts] Re: Brain Burp re Noon and the Sun!

[Clive S Carver]

Have I misunderstood "Local Meridian"?

I was thinking that it was a line of Longitude (passing through the North &
South Poles of the Earth, (as does the Greenwich Meridian), with the
locations of interest on it. But Googling "Local Meridian" gives me
something else involving the Celestial Sphere. Ie The Local Meridian is an
imaginary Great Circle on the Celestial Sphere that is perpendicular to the
local Horizon. It passes through the North point on the Horizon, through the
Celestial Pole, up to the Zenith, and through the South point on the
Horizon.

In other words what I am trying to find out is whether solar noon would be
at the same instant at say, 50.0N 3.0W and 55.0N 3.0W?

Many thanks.

Clive
 



-----Original Message-----
From: Steve Allen via time-nuts [mailto:time-nuts at lists.febo.com] 
Sent: 23 November 2023 00:18
To: Discussion of precise time and frequency measurement
<time-nuts at lists.febo.com>
Cc: Steve Allen <sla at ucolick.org>
Subject: [time-nuts] Re: Brain Burp re Noon and the Sun!

On Wed 2023-11-22T22:28:36-0000 Clive S Carver via time-nuts hath writ:
> I recently read in an internet article:-
>
> "Since solar time depends on the longitude, solar noon occurs at 
> exactly the same moment in all locations that share your local meridian."
>
> Is that correct?

Yes, mostly.

> I thought that the Latitude of the locations also comes into this?

No, unless you are worried about polar motion at the level of centiseconds.

--
Steve Allen                    <sla at ucolick.org>              WGS-84 (GPS)
UCO/Lick Observatory--ISB 260  Natural Sciences II, Room 165  Lat  +36.99855
1156 High Street               Voice: +1 831 459 3046         Lng -122.06015
Santa Cruz, CA 95064           https://www.ucolick.org/~sla/  Hgt +250 m
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