Here in the Northern Hemisphere, we call the closest full moon to the autumn equinox the Harvest Moon. In 2016, the September equinox comes on September 22. So this hemisphere’s Harvest Moon is the full moon of September 16. It happens to be an especially close and large full moon … a supermoon? There’s disagreement on that, but we can all agree that this particular Harvest Moon looks especially bright. Plus this Harvest Moon stages a subtle penumbral eclipse on the night of September 16-17, visible from half of Earth, but unfortunately not North America. Follow the links below to learn more.
What is a Harvest Moon? In skylore, the Harvest Moon is the full moon closest to the autumn equinox. Depending on the year, the Harvest Moon can come anywhere from two weeks before to two weeks after the autumn equinox.
Harvest Moon is just a name. But this full moon has special characteristics, related to the time of moonrise. Nature is particularly cooperative in giving us full-looking moons near the horizon after sunset, for several evenings in a row, around the time of the Harvest Moon.
Here’s what happens. On average, the moon rises about 50 minutes later each day. But when a full moon happens close to the autumn equinox, the moon (at mid-temperate latitudes) rises only about 30 to 35 minutes later daily for several days before and after the full Harvest moon. It happens because the ecliptic – or the moon’s orbital path – makes a narrow angle with the evening horizon near the autumn equinox.
The difference between 50 minutes and 35 minutes may not seem like much. But it means that, in the nights after the full Harvest Moon, at northerly latitudes, you’ll see the moon ascending in the east relatively soon after sunset. The moon will rise during or near twilight on these nights … making it seem as if there are several full moons – for a few nights in a row – around the time of the Harvest Moon.
That’s because this full moon is near perigee, the closest point to Earth in its monthly orbit. This full moon comes on September 16 at 1905 UTC; translate to your time zone. Perigee comes on September 18 around 1700 UTC.
So it’s not the biggest possible moon on our sky’s dome, but it’s slightly bigger than usual.
Still, in any year, you might think the Harvest Moon looks bigger or brighter or more orange. That’s because the Harvest Moon has such a powerful mystique. Many people look for it shortly after sunset around the time of full moon. After sunset around any full moon, the moon will always be near the horizon. It’ll just have risen. It’s the location of the moon near the horizon that causes the Harvest Moon – or any full moon – to look big and orange in color.
The orange color of a moon near the horizon is a true physical effect. It stems from the fact that – when you look toward the horizon – you are looking through a greater thickness of Earth’s atmosphere than when you gaze up and overhead. The atmosphere scatters blue light – that’s why the sky looks blue. The greater thickness of atmosphere in the direction of a horizon scatters blue light most effectively, but it lets red light pass through to your eyes. So a moon near the horizon takes on a yellow or orange or reddish hue.
The bigger-than-usual size of a moon seen near the horizon is something else entirely. It’s a trick that your eyes are playing – an illusion – called the Moon Illusion. You can find many lengthy explanations of the Moon Illusion by googling those words yourself.
Is this Harvest Moon a supermoon? That depends on your definition of supermoon. Read about the disagreement on whether the 2016 Harvest Moon is a supermoon, here.
Which night is the 2016 Harvest Moon for me? The full Harvest Moon for 2016 falls on September 16 or September 17, depending on your location on the globe. It happens on September 16 at 1905 UTC. In North America, the crest of the moon’s full phase comes on September 16, at 3:05 p.m. EDT, 2:05 p.m CDT, 1:05 p.m. MDT or 12:05 p.m. PDT.
Although the full moon happens during the daylight hours for the Americas, and is still below the horizon at this full moon instant, we can still say the Harvest Moon comes on the night of September 16-17. But the moon might look equally full to your eye on the night of September 15-16, or the night of September 17-18.
Meanwhile, in the world’s Eastern Hemisphere – Africa, Europe and Asia, Indonesia and Australia – the moon is above the horizon at the instant the moon turns full at 1905 UTC. The Mid-Autumn Festival in Asia is linked to this full moon.
No matter where you are on Earth, a brilliant full-looking moon ascends over your eastern horizon around the time of sunset on September 16. It climbs highest in the sky around the middle of the night, when the sun is below your feet. That’s because the moon lies opposite the sun in our sky at the vicinity of full moon. Being opposite the sun, the moon is showing us its fully lighted hemisphere, or “day” side. That’s what makes the moon look full.
Who can see the Harvest Moon penumbral eclipse? The moon will reach the crest of its full phase on September 16 at 19:05 Universal Time, to undergo a faint penumbral eclipse in the world’s Eastern Hemisphere. For us in North America, though, the moon will be beneath our horizon as it turns exactly full during our daylight hours, so we will miss out on the September 16 penumbral lunar eclipse. See the worldwide map below, and read more about this eclipse at EclipseWise.
How did the Harvest Moon get its name? The shorter-than-usual lag time between moonrises around the full Harvest Moon means no long period of darkness between sunset and moonrise for days in succession.
In the days before tractor lights, the lamp of the Harvest Moon helped farmers to gather their crops, despite the diminishing daylight hours. As the sun’s light faded in the west, the moon would soon rise in the east to illuminate the fields throughout the night.
Who named the Harvest Moon? That name probably sprang to the lips of farmers throughout the Northern Hemisphere, on autumn evenings, as the Harvest Moon aided in bringing in the crops.
The name was popularized in the early 20th century by the song below.
Shine On Harvest Moon
By Nora Bayes and Jack Norworth (1903)
Shine on, shine on harvest moon
Up in the sky,
I ain’t had no lovin’
Since January, February, June or July
Snow time ain’t no time to stay
Outdoors and spoon,
So shine on, shine on harvest moon,
For me and my gal.
And don’t miss this more recent version of the song by Leon Redbone.
When is the Southern Hemisphere’s Harvest Moon? For the Southern Hemisphere, the autumn equinox falls in March. So the Southern Hemisphere always has a full moon with these same characteristics – rising shortly after sunset for several nights in a row – in March or April.
What are some other full moon names? Every full moon has a name. The names vary in cultures around the world, and they particularly vary between the Northern and Southern Hemispheres. One of the most famous full moon names – other than Harvest Moon – is Hunter’s Moon. That’s the name for the full moon after the Harvest Moon. For the Northern Hemisphere, this year’s Hunter’s Moon comes on October 16. Read more about full moon names here.
Bottom line: Here in the Northern Hemisphere, we call the closest full moon to the autumn equinox the Harvest Moon. In 2016, the September equinox comes on September 22. So this hemisphere’s Harvest Moon is the full moon of September 16.
Deborah Byrd created the EarthSky radio series in 1991 and EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.