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$\begingroup$ Do you know which of the two inequivalent definitions of "noon" is more standard? $\endgroup$

tparker
– tparker

2026-06-28 23:14:53 +00:00
Commented 2 days ago
$\begingroup$ If I'm understanding the geometry of the solar hour angle correctly, then that's the first definition ("the moment when the Sun [crosses] the observer's meridian") rather than the second definition, correct? $\endgroup$

tparker
– tparker

2026-06-28 23:28:52 +00:00
Commented 2 days ago
3

$\begingroup$ Yes, that's correct. FWIW, here's a graph I made a few years ago using Horizons, showing how much the solar day length differs from 24 hours over the year, measured from solar noon to solar noon at Greenwich. i.sstatic.net/wmiBJ.png $\endgroup$

PM 2Ring
– PM 2Ring

2026-06-28 23:31:46 +00:00
Commented 2 days ago

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