Blue Moons are generally thought to be so rare we say “once in a blue moon” to indicate something that rarely happens. Well. A blue moon is arriving on Saturday which (witch) also happens to be Halloween!
Interestingly, a Blue Moon isn’t really that rare of an event.
I did a deep dive, got confused and re-read it all again. Here is what I understand.
There are 2 types of Blue Moons. There is a monthly Blue Moon and a seasonal Blue Moon.
The monthly one would be during a month that has 2 full moons. A seasonal Blue Moon is an extra full moon that occurs within an astronomical season. An astronomical season is defined by the dates of the solstices and equinoxes— and typically has 3 full moons within it. If a season instead has 4 full moons, then the 3rd full moon (not the 4th) in the season may be called a Blue Moon. (confused yet? Yeah, me too but this comes right from the Farmers Almanac so I will take their word for it. )
Back to a Blue Moon not being all that rare (the next one will be August 22, 2021) what is rare is a full moon on Halloween. There hasn’t been one visible to North America since 1944 and it will be the last full moon to fall on Halloween until October 31, 2039.
Oh, also? A Blue Moon doesn’t even really appear blue…so…..fake news, I guess?
