The most famous of all full Moons lights up the sky tonight: the Harvest Moon. It keeps the fields bright, allowing farmers to continue harvesting crops well into the night.

There’s not a complete agreement on how to reckon the date of the Harvest Moon. One system is simple: It’s the full Moon of September. But that doesn’t necessarily match the best time of the month for harvesting. If the full Moon comes in the first few days of the month, it might be too early to really help. And occasionally, there can be two full Moons in September — on the 1st and 30th.

So the most common system says the Harvest Moon is the full Moon closest to the autumnal equinox. That means the Harvest Moon can come as early as about September 6th, or as late as about October 7th.

This year, the equinox takes place on September 22nd. That’s 12 and a half days after September’s full Moon, and 17 days before October’s. So Harvest Moon honors go to September.

There’s a common perception that the Harvest Moon is especially bright, but that’s not the case. Brightness is determined by the Moon’s distance. But the distance isn’t synched up with the Moon’s phases. This year, the Moon was closest for the month just a couple of days ago — about 12,000 miles closer than average. It’s only a couple of thousand miles farther tonight, so the Moon will be a little brighter than average — an especially bright Harvest Moon.
 

Script by Damond Benningfield

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