SAN FRANCISCO (KRON) — The Harvest Moon will be glowing at its peak Monday night.
The Harvest Moon is the full moon that rises closest to the autumnal equinox, which is Sept. 22, officially marking the start of the fall season for the Northern Hemisphere.
According to the Farmer’s Almanac, the moonlight of the Harvest Moon brightens the early evening when crews are harvesting their summer crops.
Unlike other full moons throughout the year, the Harvest Moon reliably lights up the sky around the same time each night.
“The section of the zodiac band in which the full Moon travels around the start of autumn is the section that forms the most shallow angle with the eastern horizon,” according to The Farmer’s Almanac.
“Because the Moon’s orbit on successive nights is more nearly parallel to the horizon at that time, its relationship to the eastern horizon does not change appreciably, and the Earth does not have to turn as far to bring up the Moon,” it says.
According to NASA, the Harvest Moon will appear full for about three days this year, with peak illumination around 7:55 p.m. ET Monday night. It will last through Wednesday morning.
The autumnal equinox occurs when the sun is directly over the equator. At this time, the sun is moving from north to south. During the vernal equinox, the sun is moving from south to north. Daylight hours are roughly the same in the Northern and Southern hemispheres during the fall equinox.
After the autumnal equinox, the sun starts to rise later and it gets dark sooner in the evening. This comes to an end with the December solstice, which brings with it longer days and shorter nights.