For the first time since 2000, the Harvest Moon will rise on Friday the 13th this year –– at least for some of us.
It’s what is called a “split” full moon, since the instant of fullness will occur just after midnight on Saturday.
So New Yorkers and U.S. East Coasters who are superstitious need not fear. The actual instant of the full moon will technically fall on Saturday the 14th, at about 12:30 a.m.
A Harvest Moon is so named because it occurs closest to the autumnal equinox, which is right around the corner on Sept. 22-23 –– also split. People in the Central, Mountain, or Pacific time zones will see fall begin on Sept. 22 and the moon turn full before midnight on Friday the 13th.
The moon name’s origins are agricultural, numerical and practical.
“During the harvest season farmers sometimes need to work late into the night by the light of the moon,” according to NASA. “Usually the full moon rises an average of 50 minutes later each night, but for the few nights around the Harvest Moon, the moon seems to rise at nearly the same time: just 25 to 30 minutes later across the northern U.S., and only 10 to 20 minutes later for much of Canada and Europe.”
The particulars of a Harvest Moon vary by date but not by circumstance, as NASA shows in this video from 2013.
Even though this year’s Harvest Moon will be as plump as a juicy peach –– or a giant pumpkin –– it will actually be at its farthest from Earth for the month, making it a “micro moon,” and about 14% smaller, says the Farmers’ Almanac.
The term was first used in Europe in 1706, according to NASA’s citing of the Oxford English Dictionary.
The last time there was a split full moon it occurred in the reverse, notes the Farmers’ Almanac, when in June 2014 the moon turned full just after midnight on Friday the 13th and for the rest of the country on Thursday the 12th. The next Friday the 13th full moon won’t occur till August 13, 2049, the Almanac notes, so this one is worth noting.
Also this time of year, the moon appears full for several days in a row, EarthSky.org notes.
“This bonanza of moonlight in the season of waning daylight remains the legacy of the Harvest Moon,” EarthSky.org says. “The Harvest Moon distinguishes itself from other full moons with several nights of dusk-till-dawn moonlight.”
On the mainland U.S., the moon will turn full at 12:33 a.m. Saturday Eastern time, but at 11:33 p.m. Central, 10:33 Mountain and 9:33 p.m. Pacific, EarthSky.org says.
“The last time that the Northern Hemisphere’s full Harvest Moon fell on a Friday the 13 (for at least a portion of the world) was in the year 1935,” Earthsky.org says. “And the next time won’t be until the year 2171.