Why is it Called a Harvest Moon?

The full moon occurring closest to autumnal equinox is called the harvest moon, not simply because our temperatures will be falling and daylight hours will be less (signaling the time to harvest crops).  Its brightness as a full moon, coupled with the unusually long period it stays in the sky mean that farmers can get more work in - at this time of year the work that is typically done is harvesting.  This fortuitous timing is all due to the influence the earth's tilt has on the moon's (and the sun's) position in the sky.  Around autumnal equinox the moon rises in the northernmost point on its orbital plane.  It takes less time for the moon to reappear each night during autumnal equinox.  In fact, around the equinox the moon rises just after the sun sets, illuminating the sky and allowing farmers and gardeners alike to continue their outdoor work.  The pattern repeats itself for several days, affording a set of advantageously long days for agricultural chores.  This is the real reason for the appellation, "harvest moon."

The fact that the moon travels in it's lowest plane in the sky also influences its color.  Who hasn't seen an orange moonrise at this time of year?  The extra layer of atmosphere the moonbeams travel through bend the light to the red spectrum, huing it in a stunning shade of autumn.  See the Farmer's Almanac for a full discussion of the geometry of  moon's orbit in the autumn night sky.  Well, if you live in northeast Florida, you'll probably have to take our word for it.  The rains of 2014 continue, at least through Monday.  But keep your night watch a few more days, and you might be rewarded with a colorful moonrise and a very very bright moon, thanks to the phenomenon of a supermoon last month.

Farmers traditionally have associated the moon with moisture; it also is thought to influence other chores related to animal husbandry, fishing, and  woodworking.

Our posts this year covered winter solstice, vernal equinox, and now, autumnal equinox.  Summer solstice occurred, but we failed to note it here (we'll try again next June).   Our garden club year is about to begin.  Please consider joining us!

Photo on this posting from:  
http://neilyoungnews.thrasherswheat.org/2011/01/harvest-moon-saturday-night-live.html