The phrase "once in a blue moon" is used to denote the happening of a very rare event. Blue moons, by definition, are when there are two full moons in a single month (the term "blue moon" applies to the second full moon). Since the moon has a cycle of 29.5 days and our calendar months are generally 30-31 days in length,  the cycle only catches up about once every three years, and we have a "blue moon." This year, however, our blue moon (a full moon in Cancer) happens to fall on New Year's Eve, which hasn't happened since 1971 (and only four times since 1900); there will not be another blue moon on New Year's Eve until the year 2028. In addition to our New Year's blue Moon, we also