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harvest moon,full moon occurring nearest to the autumnal equinoxequinox
, either of two points on the celestial sphere where the ecliptic and the celestial equator intersect. The vernal equinox, also known as "the first point of Aries," is the point at which the sun appears to cross the celestial equator from south to north.
..... Click the link for more information. , about Sept. 23. During harvest moon the retardation (later rising each night) of the moon is at a minimum because of the relation of the moon's path to the horizon. On several nights in succession the moonrise is at nearly the same time, and there is full moonlight almost from sunset to sunrise if the sky is unclouded.
harvest MoonThe full Moon that occurs closest to the autumnal equinox. At this time the retardation is small (so that the Moon appears to rise at the same time on successive evenings) because of the low inclination of the plane of the Moon's orbit to the horizon.
harvest moon[′här·vəst ¦mün]
A full moon that is seen nearest the autumnal equinox.
the full moon occurring nearest to the autumnal equinox