The brightness of the Harvest Moon is an illusion. Wikipedia gives an excellent explanation: "The yellow or golden or orangish or reddish color of the moon shortly after it rises is a physical effect, which stems from the fact that, when the moon is low in the sky, you are looking at it through a greater amount of atmosphere than when the moon is overhead. The atmosphere scatters the bluish component of white moonlight (which is really reflected sunlight) but allows the reddish component of the light to travel a straighter path to your eyes."
I hope I didn't destroy your romantic illusions about the Harvest Moon with this scientific explanation! This also happens to a lesser extent with the next full moon, The Hunter's Moon.
Our eyes actually do see the low-hanging Harvest Moon as being larger than ones that ride high in the sky. This is known as Moon Illusion. I'm not even going to begin to try to explain or understand this visual or optic illusion.
In addition to color and size, the Harvest Moon is special in another way. At this time of the year, it rises about the same time the sun sets, but more important, instead of rising its normal average of 50 minutes later each night, the moon seems to rise at nearly the same time each night. The extra light these evenings gives the farmers hurrying to finish their harvest added time to work their fields. Hence the name "Harvest Moon." In some years, the Harvest Moon occurs in October.
By the way, I misquoted the lyrics to "Shine On Harvest Moon" in an earlier post. Here is the song as it is supposed to be:
"SHINE ON HARVEST MOON"
(By Norah Bayes and Jack Norworth)
"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."
I wish I could take credit for these amazing photos, but I can't. I found them on the Internet. I think the last one was digitally enhanced.