Harvest suits autumn like pumpkins suit Halloween, and September’s full moon has played a heroic role in building many a harvest tradition and festival through the ages.
The full moon nearest the fall equinox, the Harvest Moon, sits pinned low on the horizon. It hangs like some giant Jack-o-lantern, seeming to linger longer than usual for the farmers in the fields. So they can finish reaping before the frost. That's how it was.
Now, the Harvest Moon will arrive, and this year’s will be a supermoon to boot—making the autumn night sky glow even more grandly than usual.
The Harvest Moon SkinnyAt sunset, on Sept. 28, the full moon will rise in the east at 9:30 p.m. your local time. But it won't reach peak illumination until exactly 5:57 a.m. EDT the next day. So, technically speaking, it falls on the 29th.
As for its festive name, Harvest Moon garnered this traditional Western moniker for its role in, well, the harvest. As the days leading into winter grew shorter, for ages farmers labored to bring in their crops before winter set in.
Low on the horizon, the moon seemed to loiter in defiance of the very moon cycles, offering a few more hours of illumination so they might work into the night. Those were the days before they had electricity, yet the name Harvest Moon lingers today.
The Harvest Moon is also special from a scientific standpoint. Unlike other moon names, this one denotes an astronomical event; by definition, the Harvest Moon is the full moon nearest to the fall equinox. This year's equinox is on Sept. 23, at 2:49 a.m. EDT. Most other moon names—save the Hunter's Moon—are tied to their calendrical month.
Occasionally, October full moons are closer to this astronomical event, in which case they are the Harvest Moon. What of September’s full moon if that event falls in October? It takes on a different name: the Corn Moon.
- Autumn Moon (Cree)
- Falling Leaves Moon (Ojibwe)
- Leaves Turning Moon (Anishinaabe)
- Moon of Brown Leaves (Lakota)
- Yellow Leaf Moon (Assiniboine)
The Harvest Moon: A Lantern From Heaven?The Harvest Moon paired with the fall equinox is made more special for its effect of stubbornly sticking around, quite audaciously and observably, appearing to delay the moon's very orbit.
The moon circles Earth from west to east once per month, such that the moonrise is a bit later every day, by about 50 minutes on average. This daily lag gives rise to moon cycles—ranging from full moon, all the way to new moon.
How strange that this lunar schedule now changes! For a short period, just a few days during the equinox, the moon’s delay decreases to about 20 to 30 minutes, depending on where it's viewed from. Higher latitudes present less delay, or even, yes, a standstill.
The reason? The phenomenon has been called the Harvest Moon effect, and some attribute it to a peculiar angle of the elliptic—that vast imaginary plane of the solar system that the orbits of the Earth, planets, and moon generally all tend to follow—that occurs only during equinoxes. Yet it seems even mystery to many experts. A harvest miracle, maybe?
Regardless, it makes the moon stick, somehow, or appear so, letting farmers finish their work as the chill of winter creeps in.
This applies to the Northern Hemisphere; south of the equator, it's another story. Seasons are reversed with winter occurring during our summer and said special effect occurring during March's vernal equinox, six months later.
A Super Harvest MoonThe old, rural ways of society are long gone. But if farmers gaze at the Harvest Moon, they might find it brighter than usual this year. That's because it will also be a supermoon.
Supermoons are full moons that seem larger and brighter than normal. The moon's orbit is elliptical, not round, so sometimes it's closer to Earth, and at other times further away. When a full moon is near the closest point to Earth, or perigee, it becomes a supermoon.