In skylore, every full moon has many names, and most are tied to the months of the year. But some moons are tied to seasons, such as the Harvest and Hunter’s Moons.
The Harvest Moon is the full moon closest to the autumnal equinox. The Hunter’s Moon is the full moon after the Harvest Moon.
For us in the Northern Hemisphere, the 2016 autumnal equinox came on September 22, and the September 16 full moon was the Northern Hemisphere’s Harvest Moon. So the full moon on the night of October 15-16 is the Northern Hemisphere’s Hunter’s Moon, and what’s more it’s a supermoon!
Nature is particularly cooperative around the time of the autumn equinox to make the fall full moonrises unique.
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 – either a Harvest or a Hunter’s Moon – the moon (at mid-temperate latitudes) rises only about 30 to 35 minutes later daily for several days before and after the full moon. 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 result is that there’s a shorter-than-usual lag time between successive moonrises around the full Hunter’s Moon.
These early evening moonrises are what make every Hunter’s Moon special. Every full moon rises around sunset. After the full Hunter’s Moon, you’ll see the moon ascending in the east relatively soon after sunset for a few days in a row at northerly latitudes.
Hunter’s Moon is just an ordinary full moon with a special path across our sky. Most Hunter’s Moons aren’t really bigger or brighter. They’re definitely no more colourful than any other full moon. Still, many of us do think the Hunter’s Moon always looks bigger … or brighter … and more orange than usual. Why?
It’s because the Hunter’s Moon has 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 … because full moons rise at sunset. It’s the location of the moon near the horizon that causes the Hunter’s Moon – or any full moon – to look big and orange in colour.
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 full moon near the horizon – any full 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.
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