Attention sky-watchers in the Northern Hemisphere! Tonight, as you look up at the sky, the moon hitting your eye (like a big pizza pie) will be the closest full moon to the Fall equinox. The last time the beautiful harvest moon fell in October was back in 2009, so this is bound to be a treat. Make sure to keep your eyes on the horizon as the moon begins its ascent, starting at 7:21 p.m. ET tonight, October 5th.
What is the harvest moon, you ask? It's simply the closest full moon to the Autumn equinox that is usually visible in September. This year, however, the September full moon occurred early in the month (on the 6th), which makes tonight's moon the closest to the equinox and worthy of the "harvest moon" moniker.
Nasa specialist Ernie Wright gives a sense of the October harvest moon timeline: “The previous one was in 2009, but the one before that was 2006, and the next one will be in 2020.” While it's not the norm, an October harvest moon is not entirely rare. Wright calculates that the chance of a harvest moon falling in October is roughly one in four.
Harvest moons brilliantly light up the night sky, making for brighter nights than those of other seasons. This phenomenon, along with the haunting orange tint associated with the Autumn moon, is due to shorter durations between sunsets and moonrises. Historically, this nocturnal light allowed farmers to continue harvesting their crops later into the night, which could be why we now use the name "harvest moon." We do know that the name hails from Europe, where it’s been used since the early 1700s.
Different cultures have varied traditions and names for the harvest moon. Other monikers used include "blood moon," "travel moon," and "dying grass moon." While everyone holds different associations with the Fall moon, we can probably all agree that it's a beautiful sight!