The month of August will not bring us one, but two full moons! When two full moons happen in one month, the second one is called a blue moon. The second moon is nothing really special, but a moon can change color under certain circumstances, after forest fires or volcanic eruptions. Soot and ash deposited high in Earth’s atmosphere can make the moon or even the sun appear blue! The phrase “once in a blue moon” was first noted in 1824 and refers to occurrences that are uncommon, though not truly rare. Yet, to have two full moons in the same month is not as uncommon as one might think. In fact, it occurs, on average, about every 2.66 years. And in the year 1999, it occurred twice in a span of just three months. While we’ve assigned the name blue moon to the second full moon of the month, it seems that we have no such name for the second new moon of the month. Nonetheless, these opposing phases seem to be connected with each other. For if two new moons occur within a specific month, then in most cases, four years later, two full moons will also occur in that very same month. The next time we will see two full moons in a single month comes in July 2015. So get your telescopes ready, August is the month to be an astronomer!
Archive for July 30th, 2012