Tuesday, August 5, 2008

Sundial Time

Most of the United States begins Daylight Saving Time (DST) at 2:00 a.m. on the second Sunday in March and reverts to standard time on the first Sunday in November. The main purpose of Daylight Saving Time (called "Summer Time" in many places in the world) is to make better use of daylight. We change our clocks during the summer months to move an hour of daylight from the morning to the evening. So, Miami is now in Daylight Saving Time, and this photo was taken at 05 minutes past noon on my cell phone (I do not wear watches.)

For millennia, people have measured time based on the position of the sun; it was noon when the sun was highest in the sky. Sundials were used well into the Middle Ages, at which time mechanical clocks began to appear. The time indicated by the apparent sun on a sundial is called Apparent Solar Time, or true local time. This sundial at my friend the artist's house obviously cares nothing about DST, and it shows 11 AM or so.

Daily Saving Time

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