For this week’s blog post, we’re going to take a break from the usual discussions of different types of veggies, cooking styles, and gardening to focus on an astronomical phenomenon that has been incredibly important to human agriculture over the millennia. Next week, on the 23rd at 2:29 AM, the plane of the Earth’s equator will pass through the center of the sun, an event known as the Equinox. For us here in the northern hemisphere, this is the autumnal (fall) equinox, while in the southern hemisphere it is the vernal (spring) equinox. On the equinox, the length of day and night are approximately equal (though day when they are exactly equal might be one or two days off due to light refraction around the edge of the earth).
The full moon closest to the autumnal equinox is known as the Harvest Moon. This full moon often appears orange due the refracted sunlight reflecting off the surface of the moon. The Harvest Moon is unique because of the very short time between sunset and moonrise over the next two or three nights. While at most times of year the moon rises about 50 minutes later each day, at the Harvest Moon this time shrinks to about 30 minutes, meaning that there is full light for an extended period after sundown. This is the reason for the name “Harvest Moon”- before modern technology, the extended light gave farmers the opportunity to catch up on the fall harvest long after the sun set on their fields.
The Harvest Moon and autumnal equinox have taken on great cultural significance over the millennia. In Britain, the harvest festival has been celebrated near the harvest moon since before the spread of Christianity to the isles. In fact, the word “harvest” itself is derived from an Old English word, haerfest, meaning “autumn”. In revolutionary France, the monarchy was abolished on the autumnal equinox of 1792, leading the Republicans to declare the equinox “New Year’s Day” of the new Republican Era.
Do you have any plans to celebrate the Harvest Moon this year?