Why Is The Harvest Moon Orange?

The full moon in September will rise in the sky on Monday 20 September and is the Harvest Moon because it will be the closest full moon to the Autumn Equinox.

The full moon appears orange when it is nearer the horizon. This is because we see through the maximum thickness of the earth's atmosphere which absorbs blue light and transmits red light.

Why a Harvest Moon?

The term ‘Harvest Moon’ refers to the full, bright moon that is closest to the Autumnal Equinox or the start of autumn. The name is from the time before electricity, when farmers depended on the moon's light to harvest their crops late into the night.

Most years the September full moon is the Harvest Moon but every three years it is in the month of October. When the Harvest Moon falls in the month of October it means that September’s full moon can use its traditional name of Corn Moon.

Why a full moon?

A full moon occurs when the moon's earth-facing side is completely illuminated by the sun. Scientists say that when you see the moon looking really large as it rises in the sky your brain is actually playing a trick on you.

There are many reasons as to why this is, but the main theory is that when the moon is low on the horizon it can be compared to earthly things, like buildings and trees, and this is why it seems huge.



Every month of the year there is a full moon which illuminates the sky, each of which is given a different name.

There are a total of 12 full moon phases during the annual lunar cycle plus the occasional Blue Moon and each full moon has a unique name.

The traditional names given to the full moons during the year are derived from the North American traditions. Many of these ancient moon names have been given based on the behaviour of the plants, animals, or weather during that month.

However the full moon names we now use also have Anglo-Saxon and Germanic roots.

So let’s hope the sky remains clear so that we can see the Harvest Moon. It should be visible in the sky for a couple of nights either side of the 20 September.