Once in A Blue Moon, But Only Ten Years in a Decade

Winter                                    Full Moon of Long Nights

“Be always at war with your vices, at peace with your neighbors, and let each new year find you a better man.” – Benjamin Franklin

I want to weigh in on two critical debates germane to today and tomorrow.  First, the blue moon.  Current definition says a blue moon is the second full moon in the same month.  Since we had the full Wolf Moon at the beginning of December and now have the full Moon of Long Nights, this is a blue moon.  Therefore, anything you do over the next three days can be once in a. (astronomically speaking the moon is full for only a second, but the human eye can’t distinguish the difference among the night before, the night of, and the night after, so I say three days.)

Yes, Virginia, there is a second and older definition of a blue moon.*  I agree with the infoplease folks, however, that it is fussy for contemporary purposes and not as applicable to current life.  So, I agree that this is a blue moon.  Go for it.

Second debate I noticed in the newspaper letters to the editor.  A man claimed that decades receive their designation from multiples of the number 10:  2010, 2020 and so on.  Therefore, he claims our decade will not end this year, but a year from today.  He has forgotten two things.  First, the first decade is ’00–pronounced to rhyme with naughty.  That decade runs from 2000-2009.  Why? Well, as the dictionary definition says, a decade is ten years.  Count’em up.  Now the question is, at the end of the century, will we have an extra year?  Nope.  The 90’s will end in 2099 since December 31st, 2099 marks the day before 2100.  Doesn’t matter to me since time will have a much different quality for me then anyhow.

*The Other Kind of Blue Moon

May 2008’s blue moon qualified as such under an older definition, which is recorded in early issues of the Maine Farmer’s Almanac. According to this definition, the blue moon is the third full moon in a season that has four full moons. Why would one want to identify the third full moon in a season of four full moons? The answer is complex, and has to do with the Christian ecclesiastical calendar.

Some years have an extra full moon—13 instead of 12. Since the identity of the moons was important in the ecclesiastical calendar (the Paschal Moon, for example, used to be crucial for determining the date of Easter), a year with a thirteenth moon skewed the calendar, since there were names for only 12 moons. By identifying the extra, thirteenth moon as a blue moon, the ecclesiastical calendar was able to stay on track.

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