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Happy Autumn! Equinox Sept. 22
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Fall for 2012 begins in the Northern Hemisphere on September 22, 10:49 A.M. EDT.
The word equinox comes from the Latin words for "equal night." The fall and spring equinoxes are the only days of the year in which the Sun crosses the celestial equator.
... but there aren't exactly 12 hours each of daylight and night on the fall equinox:
"On the equinoxes, the very center of the Sun sets just 12 hours after it rises. But the day begins when the upper edge of the Sun reaches the horizon (which happens a bit before the center rises), and it doesn't end until the entire Sun has set. Not only that, but the Sun is actually visible when it is below the horizon, as Earth's atmosphere refracts the Sun's rays and bends them in an arc over the horizon."
http://www.almanac.com/content/first...tumnal-equinox
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