When people say “Once in a blue moon”, it’s not because the moon turns blue but because a blue moon is an uncommon site to see.
Wikipedia defines a blue moon as:
A blue moon is the “extra” full moon in years that have thirteen full moons. Most years have twelve full moons which occur approximately monthly, but in addition to those twelve full lunar cycles, each solar calendar year contains an excess of roughly eleven days compared to the lunar year. The extra days accumulate, so every two or three years (7 times in the 19-year Metonic cycle), there is an extra full moon. The extra moon is called a “blue moon.”
Last Dec. 31, 2009, many of us in Manila, Philippines looked up at the clear skies and saw a blue moon. A blue moon that falls on New Year’s Eve supposedly occurs only every 19 years.
I did not want to let the night pass without going out into the garden to see it and capture it with my trusty ol’ digicam. Here are two shots that I took:
The next blue moon that falls on a New Year’s Eve is expected in the year 2028.