If you’re a night owl, you’re in luck tonight. Across the North America, the Harvest Moon will rise. On the West Coast, peak time is 4:13 a.m. Thursday. On the East Coast, the brightest time actually happens in the morning, at 7:13 a.m. competing with the sun, which rises 33 minutes prior.
The full moon you’ll experience tonight occurs right around the time when we switch seasons to fall, also called the autumnal equinox. (It’s this Sunday, Sept. 22.) Though the Harvest Moon is an ordinary full moon, no bigger or brighter than any other, it does have some unique quirks: Typically, the moon rises about 50 minutes later each day, but around the Harvest Moon, that time difference drops to just 30 to 35 minutes, EarthSky reports.
“Every full moon rises around sunset,” according to EarthSky. “The lag time between successive moonrises shrinks to a yearly minimum … Because of this, it seems as if there are several full moons — for a few nights in a row — around the time of the Harvest Moon.”
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In addition, it also looks red or orange and huge. Those factors can both be accounted for, the former because of clouds and dust in the sky, and the latter because of something called the moon illusion, a “well-known but still mysterious trick of the eye that makes low-hanging moons appear larger than they really are,” according to a Science@NASA video (above).
The lunar event is aptly named, given its original use providing extra light for those who worked in the fields. “In the days before light bulbs, farmers relied on moonlight to help them harvest their crops,” the NASA video states. “Many crops ripen all at once in late summer and early autumn, so farmers found themselves extremely busy at this time of year. They had to work after sundown. Moonlight became an essential part of farming.”
The phrase stuck after the song “Shine On Harvest Moon” by Nora Bayes and Jack Norworth became popular in the early 1900s, according to EarthSky.
If you live in South America, your autumnal Harvest Moon happens sometime in March or April. Sorry. For the rest of you, heed the advice of NASA’s Dr. Tony Phillips: “A great pumpkin-colored moon rising in the east is a nice way to kick off northern autumn. And it’s a nice way to end the day. At sundown on Sept. 18th, go outside, face east and enjoy.”