|
Well, that depends on how you define one. According to Once in a Blue Moon, a pithy page in our Moon Phase Calendars category, there is some confusion about what constitutes a blue moon. Originally, the Maine Farmers' Alamanac based the definition of a blue moon on a tropical year, which extends from one winter solstice to the next. While most tropical years contain 12 full moons (three in each season), occasionally a year contains 13, so that one season will wind up with four full moons. The third full moon in that season is called a blue moon. The
more modern definition of a blue moon is the second full moon in a calendar month. Although this seems to be a misinterpretation of the original definition, it is more widely known and generally what people refer to when they mention a blue moon. No matter which definition you use, a blue moon isn't exactly rare. A "modern" blue moon occurs approximately every two-and-a-half years. In fact, you can catch one this November. And while we couldn't find the exact rate of occurrence of a "Famers' Almanac" blue moon, it appears
to be approximately the same.
|
