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Full Harvest Moon

The Full Harvest Moon is the full moon that occurs closest to the autumnal equinox. In most years, the Harvest Moon comes in September, but once every three or four years, it occurs in October. The full harvest moon signals that corn, pumpkins, squash, beans, and wild rice – the chief Indian staples – are ready for gathering.

Farmers welcome this full moon because it allows them to harvest well past sunset. Usually, the full moon rises an average of 50 minutes later each night, but for the few nights around the Harvest Moon, the moon rises only about 30 minutes later in the U.S. and around 15 minutes later in much of Canada and Europe. This change is due to the ecliptic (the path of the sun, moon, and planets) making a narrower angle with the evening horizon. With the moon rising earlier, farmers can continue harvesting without the usual dark period between sunset and moonrise.

The Harvest Moon often appears a reddish color as it ascends above the horizon. This is an optical illusion. When the moon is low to the horizon, it is being seen through a larger amount of atmospheric particles than if it were higher in the sky. Red wavelengths tend to travel a straighter path through the atmosphere, while the blue components tend to scatter. The full moon also appears to be much larger when it is close to the horizon, but this is only an illusion as well.

The Full Harvest Moon appears in the sky on September 15th.

Watch a video about the Harvest Moon.

Lean more about full moon names and their meanings.

See when full moons occur in 2008.