When to See the ‘Harvest Moon’ at Peak Brilliance This Month

The full moon that occurs closest to the fall equinox, which is approaching September 22, is almost upon us. Which means, for all of you, followers of the Infinite Scarf and Pumpkin Spice—crack! –fall is almost officially here. Let’s take a look at why this moon is so unique and when to see it for yourself.

What is the “Harvest Moon”?

The “Harvest Moon” behaves differently from other full moons. For several evenings before and after its peak, due to the minimum angle of the moon’s orbit from the Earth’s horizon, the moon rises above the horizon much faster than usual , shortly after sunset.

Usually when a moon is full, it rises at sunset, and then rises about 50 minutes later each day. But in the case of Harvest Moon at mid-temperate latitudes, this successively increasing rise time is halved, to 20-25 minutes. (This is even shorter in northern latitudes like Alaska, where the moon will rise at roughly the same time for an entire week.) So for several days before and after the full moon on September 20, it there will be no substantial period of darkness between sunset and moonrise. The Harvest Moon will provide a rare abundance of light from dusk to dawn.

How does the Harvest Moon get its name?

While we don’t know exactly where does the name come from, according to Earth sky, it “probably sprang on the lips of farmers across the northern hemisphere on autumn evenings as the harvest moon helped bring in the crops.” It was then popularized by a 1903 song “Shine on Harvest Moon”, written by married vaudeville duo Nora Bayes and Jack Norworth (who – side note – also wrote the lyrics to “Take Me Out to the Ball Game” ).

Hollywood films of the same name followed in the 1930s and 1940s, along with more than two dozen recordings of songs by other artists throughout the century. (Neil Young’s “Harvest Moon” is its original version, in case you’re wondering.)

Why is it orange?

The Harvest Moon has a reputation for being larger and reddish orange in color than other full moons, but this is largely a misconception. The Harvest Moon is no larger than any other full moon and its size differs each year. In 2019, in fact, it was the smallest full moon of the year; in 2020, it rose to second place. This year it will be medium in size. Although it is not necessarily closer or larger than other full moons, it can appear larger due to its location near the horizon.

Although it takes on a burnt hue of hers, this is because the moon is low in the sky, and not the color of the moon itself. Because of its proximity to the horizon, we view it through a greater thickness of the Earth’s atmosphere than when it is above our heads. The density of the air molecules diffuses more blue light, allowing more red light to pass through. The illusion of color is amplified on humid or foggy nights.

When can you see it?

The peak of the Harvest Moon 2021 is at 7:54 p.m. ET on September 20. Be sure to contemplate her tranquil majesty, perhaps while regaling your friends or family with new facts about her history, appearance, and singular attributes.