Look for the Harvest Moon to shine on the night of September 27-28, 2015. And it’s not just any Harvest Moon. It’s also a supermoon that’s staging a Blood Moon eclipse. Follow the links below to learn more.
What is a Harvest Moon? In traditional skylore, the Harvest Moon is the full moon closest to the autumnal equinox, and depending on the year, the Harvest Moon can come anywhere from two weeks before to two weeks after the autumnal equinox. For us in the Northern Hemisphere, the 2015 autumnal equinox comes on September 23, so the September 27-28 full moon counts as the Northern Hemisphere’s Harvest Moon.
By the way, this year’s Harvest Moon will present the closest and largest full moon of the year. It’ll also stage a total eclipse of the moon on the night of September 27-28.
However, the Harvest Moon isn’t always the biggest full moon of the year or more pumpkin-colored than other full moons. It’s special because, at this time of year in the Northern Hemisphere, the time between successive moonrises – from one night to the next – is shorter than usual. But this year, 2015, the Harvest Moon is a bit bigger than usual … because it’s a supermoon.
What makes this moon a supermoon? This year’s Harvest Moon qualifies as a supermoon because the moon turns full about one hour after reaching lunar perigee – the moon’s closest point to Earth for the month. Read more about the 2015 supermoons here.
Will you notice the extra-large size of this full September Harvest Moon using just your eye? Maybe.
Here’s what you can notice, if you live on a coastline. Watch for this full moon to bring along wide-ranging spring tides along ocean coastlines for several days following full moon. That is, high tides will climb extra high and the low tides will fall exceptionally low.
Which night is the 2015 Harvest Moon for me? The full Harvest Moon for 2015 falls on September 27 or September 28, depending on your location on the globe. It happens on September 28 at 2:51 Universal Time. In North America, the crest of the moon’s full phase comes on September 27, at 10:51 p.m. EDT, 9:51 p.m CDT, 8:51 p.m. MDT or 7:51 p.m. PDT.
So the night of September 27 has the brightest, fullest moon for the Americas. Meanwhile, in the world’s eastern hemisphere – Africa, Europe and Asia, the full moon comes after midnight September 28. 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 27. 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.
Can I look for the Harvest Moon on other nights? Yes. No reason to limit the Harvest Moon fun to the nights of September 27-28. At middle and northerly latitudes in the Northern hemisphere, look for the moon to come up at dusk or nightfall for a few nights in succession. This procession of moonlit nights is what characterizes the Harvest Moon.
Want to know the time of moonrise in your location? My favorite source of that information is this Custom Sunrise Sunset Calendar. Once you get to that page, be sure to click the box for ‘moon phases’ and ‘moonrise and moonset times.’
What makes a Harvest Moon special? Harvest Moon is just a name. It’s the name for the full moon nearest the autumnal equinox. In the Northern Hemisphere, the Harvest Moon most often falls in September but sometimes falls in early October. But the Harvest Moon is more. Nature is particularly cooperative around the time of the autumn equinox to make the full moonrises unique around this time.
Here’s what happens. On average, the moon rises about 50 minutes later each day. But when a full moon happens close to the autumnal 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. Why? The reason is that the ecliptic – or the moon’s orbital path – makes a narrow angle with the evening horizon around the time of the autumn equinox. The narrow angle of the ecliptic results in a shorter-than-usual rising time between successive moonrises around the full Harvest Moon.
These early evening moonrises are what make every Harvest Moon special. Every full moon rises around sunset. After the full Harvest Moon, you’ll see the moon ascending in the east relatively soon after sunset for a few days in a row at northerly latitudes. The lag time between successive moonrises shrinks to a yearly minimum, as described in the paragraph above. Because of this, it seems as if there are several full moons – for a few nights in a row – around the time of the Harvest Moon.
Is the Harvest Moon bigger, or brighter or more colorful? Not necessarily, although this year’s Harvest moon counts as the most “super” supermoon of the year.
In any year, the Harvest Moon is celebrated for featuring the year’s grandest procession of moonlit nights. And, although in most years Harvest Moons aren’t necessarily bigger or brighter or more colorful than other full moon, you might think they are. Why?
It’s true that, in some months, the full moon is closer to us in orbit than others and so truly appears bigger. That’s the case in 2015. But the distance of the full moon depends on where the moon is in its orbit. There’s no correlation between each year’s Harvest Moon and the moon’s location in orbit (the actual full moon size). It’s different every year.
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 lengthy explanations of the Moon Illusion by googling those words yourself.
The shorter-than-usual 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 8. Read more about full moon names here.
Bottom line: The Harvest Moon in 2015 comes on the night of September 27-28. It’s a supermoon, or full moon closest to Earth for the month, and in fact it’s the closest supermoon for this year. What’s more, the Harvest Moon will stage a total lunar eclipse on this same night.
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.