In fact, you can witness the moment when the Moon takes on a pink-orange hue… each month, and September 2022 is not an ideal month to observe the beautiful Moon illusion, as it appears much smaller compared to the Moon in May, June, July, and August.
“Harvest Moon” rising in September is a long-standing legend in Western countries, much anticipated like the “Pink Moon” in April. However, one truth is that the Moon does not actually change color as one might expect.
According to Earth Sky, the Moon can be observed each month for a moment with a pink-orange hue, as long as you catch the phenomenon of “Moon illusion.”
Graphic illustrating the “Moon illusion,” where the atmosphere acts as both a lens and a prism, making the Moon appear larger and redder when it is lower in the sky (just risen or about to set) – (Image: BBC SKY AND NIGHT MAGAZINE).
“Moon illusion” occurs when the Moon rises at sunset; it is entirely a common physical phenomenon. This pink-orange color is due to the fact that when the Moon is low on the horizon, you are viewing it through a thicker layer of atmosphere. As the Moon rises higher, the layer of atmosphere you have to look through becomes thinner.
This thick atmosphere creates an effect that makes the Moon appear slightly redder than usual, typically in a light pink-orange hue.
“This has nothing to do with the Harvest Moon (i.e., the Moon in September). Both the Moon and the Sun appear redder when they are near the horizon. The reason for this is that we are seeing them through the maximum thickness of the atmosphere, which absorbs blue light and transmits red light,” explains Professor Emeritus John Percy from the Department of Astronomy and Astrophysics at the University of Toronto, Canada, in an analysis published on PHYS.
Moreover, this layer of atmosphere also acts as a lens, causing the Moon to appear larger than usual.
The September Moon is referred to as the Harvest Moon by Westerners because it is associated with the harvest season, a time when farmers can easily look towards the horizon.
The legend of the “Burning Orange Harvest Moon” leads many to eagerly await the moment the Moon rises, so many will witness the Moon illusion instead of overlooking it as in other months, mistakenly believing it has changed color.
From an astronomical perspective, the Moon near the time of the autumn equinox or spring equinox will appear fuller than usual from the Earth’s viewpoint; however, to the naked eye, you will not notice any difference.
In 2022, September will not be the time to observe the Moon illusion or the largest full Moon of the year, as the September Moon, while still within the vicinity of Earth in its elliptical orbit, does not reach the level of a “supermoon” like the supermoons in May, June, July, and August.
This means that the September Moon will be smaller than the Moons of the previous four months.
If you want to observe the Moon with a reddish-orange hue high in the night sky, your only option is to wait for a lunar eclipse, also known as a “blood moon.”
A little historical “trick” also often occurs with the Pink Moon, which is the Moon in April, named after the blooming season of pink phlox flowers across North America.
Of course, this Moon does not turn pink unless you see it during the Moon illusion, when any Moon takes on a pink-orange hue.
For these reasons, if you missed the moment of the “Orange Moon” last night, you can still wait for sunset today, choose an open observation point where you can see the horizon, and… hope for good weather with few clouds. The Moon illusion will occur as soon as the Moon rises, regardless of whether it is perfectly full or not.
