Originally Posted by
steelbikeguy
ah yes... the key word is "analemma".
If I understand correctly, the time when the sun is at the center of its travel from east to west would normally be considered noon, but due to the varying speed caused by the elliptical orbit, it will occur a bit earlier or later than a mechanical clock would predict.
As others have noted too, it's nice to understand the weird figure 8 that would be printed on globes, back when people still had globes.
Steve in Peoria
Everyone should own a globe. I pored over mine when I was a kid. Africa is enormously bigger than Canada and Greenland. It is useful today for Europe to visualize that an ICBM launched from North Korea could hit Munich (if it had the range) in less time than it would take to reach Chicago. Only on a globe can you see this. I'm getting one for my grand-daughter as soon as she's old enough. Two-and-a-half is still a bit young.
As described in
https://en.wikipedia.org/wiki/Longitude_by_chronometer, the Equation of Time (which is what an analemma depicts graphically) must be consulted to correct local determinations of noon when using a marine chronometer to calculate longitude at sea, a feat previously considered impossible. This was especially so for long voyages of exploration to the South Seas (where the analemma lives on globes to this day!) Controlling scurvy and finding the longitude made the British Empire possible. Dava Sobel's book,
Longitude: The True Story of a Lone Genius Who Solved the Greatest Scientific Problem of His Time is highly recommended.