Full moon to spark eruption? Once in a blue moon

The New Year will be ushered in by a full moon, bathing outdoor celebrations with its soft light. At least one government scientist suggests a less benign effect: the full moon’s gravitational pull could hasten the eruption of Mount Mayon. However, this is a notion that has previously been debunked. In an interview with reporters yesterday, Julio Sabit, Phivolcs spokesperson and science research specialist, said that the full moon tonight could help intensify volcanic activity. "The chances of a full moon itself causing an eruption are very minimal," he explained, “but it could trigger one if the volcano is already about to erupt." The moon’s gravity has been scientifically proven to affect the Earth, mostly through the changes in the Earth's tides, which are highest during full moons. However, no similar connection has been proven between the moon and volcanic activity. Full moons coincide with Mayon eruptions? The notion of a full moon triggering an eruption of Mayon has been advanced before, at one time even broadcast by the BBC during a previous restive period for one of the world’s most active volcanoes. The BBC reported that “a full moon coincided with at least three of Mayon's 47 eruptions, including the two most recent ones in 2000 and 2001." That “coincidence" was quickly labeled a “weak link at best," according to astronomer Phil Plait on his blog. “Statistically speaking, the Moon has nothing to do with eruptions," Plait writes. “If it did, you’d expect to see a bump in the number of events near the full Moon. But the number of eruptions near the full Moon is what you’d expect from random chance." A blue moon in name but not in color The full moon tonight is also “a blue moon," which, in the astronomical sense, has nothing to do with its color but with being the second full moon in the same calendar month. The last full moon was on December 2. The rarity of this event led to the expression “once in a blue moon." In the early days of Christianity, celebrations such as Christmas and Easter were closely tied to the harvest seasons and the lunar cycle. The celebration of Lent, in particular, was closely linked to the appearance of the full moon in late winter. Sometimes, however, there would be an “extra" full moon in the cycle, making it seem that the winter moon had come too early or too late. This additional moon was called a “betrayer" moon or, in Old English, a “blewe moon." Volcanic ash as optical filter Yet no matter how you squint at it, a blue moon won’t appear to be literally blue. That is, not unless there’s a large-scale volcanic eruption. In 1883, the explosion of Krakatoa volcano in what is now Indonesia sent up into the atmosphere particles of ash that were fine enough to serve as a kind of optical filter. As a result, the normally white moonlight turned a light shade of blue. We may be able to see just such a blue moon if and when Mount Mayon in Bicol explodes, emitting a large enough ash cloud with the right kinds of particles. Volcanic ash could give the impression of a blue-colored moon if the particles are about one micron in size. – Howie Severino with Sophia Dedace in Albay and TJ Dimacali, GMANews.TV