So long sweet summer – autumn is here, and will enter with a celestial bang this year.
Tonight marks the official fall kickoff – meaning we’re one step closer to winter and skiing – with the autumnal equinox occurring at 11:09 p.m. Eastern Standard Time. As an added bonus, it will be greeted with a full moon, signifying the rare “super harvest moon.”
The “harvest moon” is the full moon that happens closest to the yearly autumnal equinox, or the time when day and night are equal in length each September. The harvest moon phenomenon was named for farmers who used to depend on the moonlight to extend the workday during the busy harvest season. With the harvest moon there is no long period of darkness between sunset and the moon rising.
But for the super harvest moon to occur, the two events must fall on the same night.
When these two occurrences mix together, sky-watchers are treated to a sort of 360-degree twilight glow effect that is rarely visible. The so-called super harvest moon has not occurred for 20 years, and will likely not reappear until 2029.