Wednesday, September 18, 2013

Shine On Harvest Moon

The Autumn Equinox occurs on September 22 this year.  This is the date when the Sun shines directly over the equator at noon.  The amount of daylight and darkness is the same at equal latitudes north and south. 


Hartford, at 41.7627° N will receive 12 hours, 9 minutes, and 11 seconds of sunshine. At 41.7627° S, in southern Argentina, you would also get 12 hours, 9 minutes, and 11 seconds of sunshine.


While you will hear lots of talk about September 22 being the first day of autumn, it really isn't.

Astronomers use the equinoxes and solstices to divide the astronomical seasons, but we live on Earth, not in the stars.


For the Biosphere, the changing amount of sunlight over the year signals the seasons.  Around August 1st, the Biosphere's first day of autumn, the shortening day starts the fruit and grain to ripen.  By mid-autumn, the equinox, the harvest is in full swing, with more tomatoes and apples than we can eat.



That is why the Harvest Moon is important.  The Harvest Moon is the full moon closest to the autumn equinox.  This year, in Connecticut, it arrives on the 19th, just after sunrise.


What does that signify?  With all of that ripening grain and fruit, there was not enough time in the day to harvest it all.
“In the days before electric lights, farmers depended on bright moonlight to extend the workday beyond sunset,” writes NASA’s Dr. Tony Phillips. “It
was the only way they could gather their ripening crops in time for market. The full moon closest to the autumnal equinox became the Harvest Moon, and it was always a welcome sight.”

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