Tonight’s full moon is a ‘blue moon’, except it’s not… except it is…
Joe Rao over at space.com explains:
The full moon of November arrives on Sunday and will bring with it a cosmic addition: It will also be a so-called “blue moon.”
“But wait a minute,” you might ask. “Isn’t a ‘blue moon‘ defined as the second full moon that occurs during a calendar month? Sunday’s full moon falls on Nov. 21 and it will be the only full moon in November 2010. So how can it be a ‘blue’ moon?”
Indeed, November’s full moon is a blue moon – but only if we follow a rule that’s now somewhat obscure.
It’s a pretty fascinating story, all told. And there’s probably a lesson in there about how we now quantify using months instead of seasons, and how that parallels the shift from a more agrarian lifestyle or something. Either way, it’s a good excuse to have a beer and toast our natural satellite.