Tuesday, June 26, 2007
June 2007 can boast a Blue Moon . . . No it’s not just a variety of Coors beer . . . or the title of a lovelorn song . . . that’s when the full moon appears twice in the same month. The first full moon this month took place on 1st June and the 30th will be full also. There is a blue moon once every two or three years so it’s not that rare an event despite the ‘once in a blue moon’ phrase meaning rarely, becoming folklore. Over the next twenty years there will be a total of 17 blue moons. No blue moon of any kind will occur in the years 2006, 2011, 2014, and 2017. How do I know . . because I read it on a NASA sight in an effort to get in touch with my inner geek.
Two full moons in one month may occur in any month out of the year except for February, which is shorter than the lunar cycle.
There have been occasions when the Moon has appeared to be blue in hue. This isn't an astronomical phenomenon. Instead, it is caused by dust or smoke high in the Earth's atmosphere. The dust is thrown up by major volcanic eruptions such as Krakatoa, Mount St. Helens or Mount Pinatubo, whilst smoke can come from large forest fires.
A blue moon was reported during forest fires in Sweden in 1950 and Canada in 1951. People reported seeing a blue moon for nearly two years after the eruption of Krakatoa in 1883. California may have a blue moon due to the recent spate of bush fires. Hawaii too may have one due to the regular tantrums put forth by Kilawau. Who knows, maybe even Beijing’s pollution will reveal a bluey tinge on the old sattelite.
Whether it's dust or smoke, the tiny particles have a strange effect on the moonlight (or sunlight) passing through them. If the air is damp and heavy, the water droplets scatter red and green light, allowing other colours to pass. They scatter the light in every direction, but red light is scattered more strongly than blue light, so that less red light passes directly through the dust or smoke. Thus the Moon has a blue tinge. A white moonbeam passing through such a misty cloud turns blue. Clouds of ice crystals, fine-grained sand, volcanic ash or smoke from forest fires can have the same effect.
Will you see a blue moon this month? Have a look at the night sky on June 30. Well, I will be because I like the concept, it’s sort of ethereal and romantic.
Look out, the lunatics are on the grass . . .