For the first time in nearly two decades, this year’s Harvest Moon will fall on the most haunted date on the calendar.
The Harvest Moon is the full moon that occurs closest to the autumnal equinox in the Northern Hemisphere. This year’s autumnal equinox is on Monday, September 23, and the full moon that falls closest to it is this Friday the 13th.
The Harvest Moon was so named because farmers could get in extra labor at harvest time working by the light of the full moon. Many of its other names—the Barley Moon, the Corn Moon, and Fruit Moon among them—also allude to its agricultural origins.
That last time this confluence happened was 2000, when the Harvest Moon happened on Friday, October 13. And you’ll have to wait until August 13, 2049 for it to happen again.
The Harvest Moon tends to stick closer to the horizon, which means it looks bigger and has a redder hue than a typical full moon. The former is an optical illusion—things just look bigger near the horizon—while the latter has to do with the light reflect off of the moon passing through the maximum thickness of the atmosphere, which absorbs blue and transmits red light.
So if you’ve been meaning to celebrate the start of fall and/or pick the fruits and vegetables in your backyard garden, this Friday is a good a day as any to collect your harvest and toast your farmer forebears.