Every month’s full moon tells us a little about the season. That’s why the Cold Moon happens in February and May’s moon is named for flowers. The Harvest Moon refers to the late summer-early fall harvest time, which many of us partake of in a small way with our gardens. My tomato harvest just wrapped up, but there’s still a zucchini or two on the way.
The Harvest Moon is the full moon that occurs closest to the autumnal equinox, the first day of fall in the northern hemisphere. This year that happens overnight on Sept. 18-19. Since full moon dates bounce around a bit, the Harvest Moon can happen anywhere from mid-September to mid-October, making it the only full moon to carry the same name in two different months.
The Harvest Moon harks back to our agrarian past when farmers used its welcome light to continue harvesting their crops past sundown. WIth electricity, moonlight was important part of farming. Once the crop was ripe, you needed to gather it up as soon as possible, and that could mean working into the night.
It’s the Harvest Moon’s angle to the horizon that makes it unique and useful. Because the angle of the full moon’s path to the horizon is very shallow in September and October, the time difference between successive moonrises is only about 20-30 minutes instead of the usual 50-60. With moonrise happening on the heels of sunset, the Harvest Moon’s return at practically the same hour gave farmers nearly continuous light from sunset to sunrise to work the crops.
Night to night the moon moves about 12 degrees along its orbit or a little more than one fist held at arm’s length to the east. You can see this for yourself by referencing the moon’s location with respect to a bright star in its neighborhood.
Around the time of September’s full moon, a significant amount of that 12 degrees is toward the north direction which causes the moon’s path at the horizon to flatten out. A shallow path means the moon’s eastern movement only puts it a little bit further below the horizon for several nights around full moon. Earth only has to rotate for 20 to 30 minutes to carry the moon into view. Six months ago at the spring equinox, the full moon’s path was much more steeply tilted to the horizon and night to night rising times more than an hour apart.
That’s why I call spring the time-when-the-moon-gets-out-of-the-sky-in-a-hurry as opposed to the current full moon that never sleeps. While I’ve been known to gather my garden goodies by moonlight when frost threatens, most of us can take advantage of the full moon’s slanted path to enjoy night after night of watching a big moon rise without to stay up late. Consider it a harvest of moonlight and a veritable feast for the eyes.
Since full moon occurs during the early morning hours of the 19th across the Americas, the moon will look almost identically full on both Sept. 18 and 19. Two nights of the Harvest Moon – can it get any better? Click HERE to find out when the moon rises for your town. If you take a photo, please send me a copy at firstname.lastname@example.org. I’ll publish a little gallery on the 20th. Thanks!