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Rick Williams
Woodland, CA
06/21/2019
01:00 pm

Equipment Details:

iPad

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This photo has never been submitted anywhere before. I can take one tomorrow if a more recent photo is preferred.

Image Details:

This picture was taken at Noon (1 PM PDT) on June 21, 2019, the solstice. A small, stationary mirror on the ground reflects sunlight onto the wall. Each day I marked the position of the light at exactly 12 Noon (1 PM Pacific Daylight Time). Over the course of a year, connecting the position of the sun forms an analemma. At the solstice (sol= sun, sistere= to stand still) the declination of the sun seems to “pause” at its northern limit before reversing direction. On any given day, a horizontal line shows the latitude at which the sun is directly overhead at solar noon; in this case, 23.5 degrees North. If a vertical line is dropped from the sun’s position to the minute scale (below the 10 degree N line), solar time can be seen to be 9-10 minutes slower than standard time (9 m 2 s exactly, corrected for my longitude). A very accurate sundial would thus be 9 minutes slow on this date and one would add 9 minutes to obtain standard time. This is the same analemma that one sees floating out in the Pacific Ocean on globes, and the explanation of the horizontal equation of time scale, which shows the difference between solar and standard time at the Prime Meridian.