NASA/YouTube
The harvest moon is giant and red upon the horizon because it rises at sunset.

That Big Pumpkin in the Sky: Harvest Moon Really Shines This Week

ICTMN Staff
9/19/13

The harvest moon is still upon us, as the fall equinox approaches this weekend.

The fullest moon of the month fell on the night of September 18-19, but as NASA points out in this video, the moon is in the midst of a string of days during which it rises at sunset. And when that happens, the horizon-moon illusion combines with the sunset colors to redden it.

“When you add these effects together the Harvest Moon often looks like a great pumpkin,” NASA says. “The experience is repeated for several nights in a row around the equinox.”

So check the horizon tonight for a giant pumpkin. The fall equinox arrives on Sunday September 22. 

ScienceCasts: The Harvest Moon

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