Bye bye blue moon

The last blue moon until 2015 sets in a crystal clear San Diego sky.

A blue moon isn’t really blue. It’s the second full moon in a month. This August there were two full moons so the one that rose on August 31st and set on September 1st is a “blue moon.” The next blue moon is in 2015. The term “blue moon” is an expression denoting a rare event such as, “once in a blue moon.”