The moon will be full Monday -- the Harvest Moon, the best known of all the year’s full moons. It is the moon of song, poetry and folklore and a herald of autumn and ripening fields.
Before farmers had mechanical pickers and electric lights, they relied on the light of the Harvest Moon to bring in their crops. Back then, most of the harvesting was done by hand. With everything ripening at nearly the same time, there was too much work to be done in the fields to stop at sundown. A bright full moon allowed farmers to work long into the night to reap the crops at peak harvest time. Many farmers said the moonlight gave them the equivalent of an extra day or two.
The Harvest Moon also appeared at the time that some of the basic staples of Native Americans -- beans, corn, beans, pumpkins, squash, wild rice, wild nuts and fruits -- were ripe for harvesting. The Cherokees called September‘s full moon “The Nut Moon,” said David Dundee, an astronomer with the Tellus Science Museum. Other Native Americans called it the “Full Corn Moon.”
By astronomers’ definition, the Harvest Moon is the full moon closest to the autumnal equinox, or the first day of fall, when day and night are in almost perfect balance with one another. Thus, in some years, the Harvest Moon occurs in October. (The fall equinox this year occurs on Sept. 23; after that, the next full moon is on Oct. 11)
The Harvest Moon has the reputation of being the biggest, brightest and “fullest” moon of the year, but that is not necessarily so. In fact, this year’s Harvest Moon may be one of the smaller full moons of 2011. A possible reason for the misconception is that people -- especially in rural areas -- over the centuries have paid closer attention to the rising of the Harvest Moon than other full moons, and thus thought it bigger. A full moon indeed looks very big as it rises after sunset in the east -- a trick of the eye known as “moon illusion.”
Still, the Harvest Moon is no ordinary full moon. Throughout the year the moon rises, on average, about 50 minutes later each day. But near the autumnal equinox, the day-to-day difference in the local time of moonrise is only 30 minutes. The shorter-than-usual time between moonrises around the full Harvest Moon means no long period of darkness between sunset and moonrise for days in succession. As the sun’s light fades in the west, the full moon rises a short time later to light up the countryside for several more hours.
While you're gazing at the full moon during the next few days, ponder this fact from NASA: Moonlight robs color from whatever it touches. A red rose, for instance, may be brightly lit and even cast a shadow in moonlight, but the red is gone, replaced by shades of gray. The entire landscape will appear this way -- like watching TV in black-and-white.
In the sky: Elsewhere in the sky, Mercury is low in the east just before sunrise, Dundee said. Mars is low in the east about three hours before sunrise. Jupiter rises out of the east a few hours after sunset. Venus and Saturn can't be easily seen this month.
