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

[Bob kb8tq]

Hi

Since we’re not confused enough already :) :) :).

Let’s say you are *really* picky about this. You are at the example location of 55.0 N  3.0W. You are standing on dry land. You don’t have a solid view of the horizon. You want to do this to find local noon and set your watch. What do you use to find “straight up”? ( ….noon is when the sun is straight overhead). 

You might say that a plumb bob will tell you straight down and go from there. The gotcha is that local geology will skew that ever so slightly. If you want to set your watch to nanoseconds of “correct", that’s going to get in the way. At the precision most folks set their watch …. not a big deal. 

Bob

> On Nov 23, 2023, at 5:17 AM, Clive S Carver via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> 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
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