It’s a pretty rare event. It happens only once every three years or so. The last one was in December, 2009. The next one is in July, 2015. A full moon at 1:58 this afternoon becomes the second full moon this month. The second full moon in a month is called a blue moon.

Why is it called a blue moon? It doesn’t have anything to do with the color of the moon. Blue moon comes from the Middle English word “belewe” meaning betray.

Easter always is the first Sunday following the first full moon of spring. But back in the days when they changed over to the Gregorian calendar, nobody really was sure when Easter was. So they depended on the church to tell them. Some people started planning for Easter when they saw the full moon only to be disappointed to learn they’d have to wait another month and continue their Lenten fast. They called that the belewe or betrayer moon.

And isn’t it strange that on the day of the blue moon, we say goodbye to the first man to set foot on the moon. The funeral of astronaut Neil Armstrong will be held today in Cincinnati.