December 6, 2010
A sidereal day is approximately 23 hours, 56 minutes, 4.091 seconds. That corresponds to the time it takes the Earth to complete one rotation relative to the vernal equinox. Since the vernal equinox precesses (every 26,000 years) in a westward direction relative to the fixed stars, the sidereal day is some 0.008 seconds shorter than [...]
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November 11, 2010
Since the dawn of time, human beings have relied on the cycles of the sun, the moon, and the constellations through the zodiac in order to measure time. The most basic of these was the motion of the Sun as it traced an apparent path through the sky, beginning in the East and ending in [...]
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