For the first time in almost 20 years, northern autumn is beginning on the night of a full Moon. The coincidence sets the stage for a “Super Harvest Moon” and a sky show to mark the change of seasons and begins at sunset on Sept 22nd, the last day of northern summer. As the sun sinks in the west, bringing the season to a close, the full Harvest Moon will rise in the east, heralding the start of fall. The two sources of light will mix together to create a kind of 360-degree, summer-autumn twilight glow that is only seen on rare occasions.
From summer to fall on Sept. 22nd at 11:09 pm EDT and at that precise moment, called the autumnal equinox, the Harvest Moon can be found soaring high overhead with the planet Jupiter right beside it. The two brightest objects in the night sky will be in spectacular conjunction to mark the change in seasons.
The Harvest Moon gets its name from agriculture in the days before electric lights. Farmers depended on bright moonlight to extend the workday since it was the only way to gather their crops in time for market.
Usually, the Harvest Moon arrives a few days to weeks before or after the beginning of fall. This one of 2010, however, reaches maximum illumination a mere six hours after the equinox. This has led some astronomers to call it the Harvestest Moon or a Super Harvest Moon. There hasn’t been a coincidence that compares to this one since Sept 23, ’91, when the difference was about 10 hours, and it won’t happen again until the year 2029.