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

[Clive S Carver]

Thank you all for the answers to my questions about Local Meridian.

I can safely advise that I accept that solar noon occurs at exactly the same
moment in all locations that share your local meridian. 

I had a similar struggle 60 years ago regarding Single Sideband
transmission. Once it clicks, it is so obvious!

Thanks again.

Clive

-----Original Message-----
From: Clive S Carver via time-nuts [mailto:time-nuts at lists.febo.com] 
Sent: 22 November 2023 22:29
To: time-nuts at lists.febo.com
Cc: Clive S Carver <clive at ancient-mariner.co.uk>
Subject: [time-nuts] Brain Burp re Noon and the Sun!

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

My reason for doubt, based on reading elsewhere, is Axial Tilt, also known
as obliquity, which is the angle between an objects rotational axis and its
orbital axis, which is the line perpendicular to its orbital plane.  The
rotational axis of Earth, for example, is the imaginary line that passes
through both the North Pole and South Pole, whereas the Earth's orbital axis
is the line perpendicular to the imaginary plane through which the Earth
moves as it revolves around the Sun; the Earth's obliquity or axial tilt is
the angle between these two lines and is about 23 degrees.

Thus to me, looking at the Earth from a distance, a Meridian will not be in
line with the Earth's Axis (other than twice each year) and this would cause
noon  at two or more different Latitudes on the same Meridian to be at
different times.

I realise that there are other complex variables involved, ie The Equation
of Time.

I am in the UK so tend to think in terms of the Greenwich Meridian and am
considering the case of two locations on the Greenwich Meridian, but could
be any other Meridian.

(For twenty years as a Merchant Navy RO, I supplied the Radio Time Signal
for the Navigators to keep the chronometer accurate; I wish now that I had
taken more notice of their sextant and tables.)

Many thanks.

Clive

 

 

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