Harvest Moon

The Harvest Moon is the Full Moon that falls closest to the autumnal equinox (around September 22–23 in the Northern Hemisphere), and it's one of the few named Full Moons with a genuine astronomical quirk behind the name — not just a folklore label. Normally, the moon rises about 50 minutes later each night. Around the autumn equinox, the angle of the moon's orbit relative to the horizon is shallower, so it rises only about 20–30 minutes later each night for several nights in a row. Before electric light, that meant several extra evenings of usable moonlight right when farmers needed it most for late harvesting — hence the name, recorded in English usage since at least the early 1700s. Because it's defined by proximity to the equinox rather than a fixed month, the Harvest Moon usually falls in September but occasionally lands in October, whichever Full Moon is nearer the equinox that year. In the Southern Hemisphere, the equivalent Moon (tied to the March equinox) doesn't carry the same name in most traditions.