Corn Moon: September's full moon

Corn Moon or Harvest Moon: the rule

September’s full moon has a name that depends on the year.

The Harvest Moon is defined by the calendar of the sky, not the calendar on the wall. The Old Farmer’s Almanac and NASA both define it as the full moon nearest the September (autumnal) equinox. The Farmers’ Almanac, a separate publication based in Maine, adds that this means it is not fixed to September.

In most years, September’s full moon is the closest one, so it takes the name Harvest Moon. When September’s full moon comes early in the month, October’s full moon can be closer to the equinox. In those years October gets the Harvest Moon, and September’s full moon goes by Corn Moon. The Old Farmer’s Almanac says the Harvest Moon lands in October about every three years. The dates above follow this rule, which is why most years have no Corn Moon at all.

Where the name Corn Moon comes from

The name points to the end of the growing season, when corn is ready to harvest. NASA’s former monthly full moon guides report that the Maine Farmers’ Almanac first published “Native American” full moon names in the 1930s. According to that almanac, Algonquin tribes of what is now the northeastern US called this the Corn Moon, the time to gather corn, pumpkins, squash, beans and wild rice. As NASA presents it, the attribution comes from the almanac, and it is not a tribal source.

The Old Farmer’s Almanac, which is based in New Hampshire, calls Corn Moon a Native American name that the explorer Jonathan Carver came across in the 1760s. Carver’s account is a colonial traveler’s record. It helps date the name, but it does not show which community used it.

Neither source supports calling this “the” Native American name. Moon names varied by nation, region and dialect, and the almanacs fixed them to Gregorian months for convenience. Our full moon names overview explains the history.

Other names for September’s full moon

The Old Farmer’s Almanac credits these names to particular nations. These are its attributions, which we have not confirmed independently.

• Corn Maker Moon: Western Abenaki.
• Corn Harvest Moon and Moon When Rice Is Laid Up to Dry: Dakota.
• Autumn Moon, Mating Moon and Rutting Moon: Cree.
• Falling Leaves Moon: Ojibwe.
• Leaves Turning Moon: Anishinaabe.
• Moon of Brown Leaves: Lakota.
• Yellow Leaf Moon: Assiniboine.
• Child Moon: Tlingit.

NASA lists two European names, Fruit Moon and Barley Moon, for the ripening fruit and the barley harvest. Indian Country Today (ICT), a Native-run news outlet, gives the Ojibwe name Waatebagaa-giizis, the Leaves Changing Color Moon.

ICT’s Dakota list gives Wayuksapi wi, the Corn Harvest Moon, matching the almanac. The Oneida name for September translates as “Someone Harvests,” and the Diné (Navajo) name as Big Harvest.

What makes the Corn Moon notable

A Corn Moon year is an early-September full moon, so the equinox is still a couple of weeks off. It still shows some of the Harvest Moon’s best-known trait. Near the September equinox, the Moon rises only a short time later from one evening to the next, instead of the usual average of about 50 minutes. NASA gives about 25 minutes at the latitude of Washington, DC around the Harvest Moon. For a Corn Moon the effect is present but weaker, because it is further from the equinox. The Harvest Moon page explains why it happens.

How to watch the Corn Moon

The table above shows the moonrise time for major cities on the best evening. Look east, just around sunset. Because successive moonrises are close together this time of year, you can watch the nearly full Moon come up soon after sunset for several evenings in a row.

The low Moon will look oversized and orange. The color is real: the Moon’s light crosses more air near the horizon, which scatters away the blue. The size is not. NASA notes that photographs show the Moon has the same width at the horizon and high overhead. The Moon illusion is in how our brains judge size against the landscape.