Upon a Harvest Moon

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.

------------------------

 



The Harvest Moon, the full moon nearest to the autumnal equinox, came upon us September 18-19. So, what is it that makes the harvest moon unique among full moons?

You might have noticed the Harvest Moon rising around sunset a few days in a row. On average, the moon rises about 50 minutes later each day. However, when a full moon happens close to the autumnal equinox, the moon rises 30-35 minutes later daily for several days before and after the full Harvest Moon. This is due to the moon’s orbital path making a narrower angle with the evening horizon which results in shorter than usual moon rising times.

The mystique surrounding the Harvest Moon leads to thoughts of bigger, brighter & more colorful/orange moons. This illusion (the "Moon Illusion") is due to the location of the moon near the horizon. When you look at the horizon, you are looking through a greater thickness of the Earth’s atmosphere than when looking overhead. All atmosphere scatters blue light (causing the sky to look blue to us). Also, the greater the thickness of atmosphere at the horizon, the greater the amount of red light passing through which thus gives the moon an orange color as it rises. 

The Harvest Moon was likely named by farmers, who could harvest their crops long into the night with the help of the lengthier moonlight.