Harvest Moon above the Valley of the Moon

Photographer: Christine Churchill
Summary Author: Christine Churchill; Jim Foster

The photo above shows the creamy harvest Moon setting behind a ridge of Douglas firs and coastal redwoods in the Valley of the Moon (where else) near Kenwood, California. Many more of us notice the full Moon when it rises than when it sets, since we’re more apt to be up and about in the early evening than in the early morning hours. Its apparent huge size is a result of the Moon Illusion effect: celestial objects near a horizon, either a natural or man-made horizon, tend to appear much larger than their actual size. The harvest Moon isn’t any bigger than other full Moons. However, because it rises near the equinox, there’s a relatively short period of time between sunset and moonrise -- in the mid-latitudes. Thus, on preceding and successive evenings the harvest Moon provides a bit more light for chores, ball games and harvesting. It needs to be mentioned that this added light applies only to the rising harvest Moon and not its setting counterpart. Note that the harvest Moon is the full Moon closest to the autumnal equinox, whether in September or October. See also the Earth Science Picture of the Day for December 23, 2007.

Photo details: Sony A350 camera; F5.6; 1/250; 400 ISO; 300 mm lens. Photo taken on October 4, 2009 at 7:13 a.m.

Valley of the Moon coordinates: N40.14242, W117.15427