Column One: Blinded by the light of the silvery moon

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The Independent Online
A RARE conjunction of millennial angst and astronomical lunacy has combined to give the world the impression that this month's full moon is the brightest for centuries.

Last night's winter solstice was supposed to have been marked by the longest and brightest full moon in generations, fulfilling an apocalyptic vision prophesied in the Book of Revelation.

It all began with an article in The Old Farmer's Almanac, which has been tracking heavenly events and seasonal changes since 1793. Some readers had the impression that this month's "astonishing lunar illumination" would be the brightest since 1866.

The reason was apparently to do with the moon's elliptical orbit coming closest to the earth, making its disc appear larger in the sky. At the same time the earth-moon system would make its closest pass to the sun, capturing more light in the process.

That the whole event should take place when the moon was at its fullest and on the same night as the winter solstice made the conjunction even more unusual.

However, in the cool light of the shortest day of the year, astronomers have concluded that there was nothing exceptional about last night's full moon. Most people would have failed to notice a thing, according to Fred Schaaf, contributing editor of Sky and Telescope magazine.

It turns out that having a full moon at a winter solstice at the same time as the lunar perigee - the moon's closest approach to earth - is not that rare. It also occurred in December 1991 and 1980, for instance.

"What is really rare," says Sky and Telescope magazine, "is that in 1999 the three events take place in such quick succession." Having all three occurring within 10 hours of each other is unmatched at any time in more than 150 years, the magazine says.

However, that on its own would not result in the brightest full moon. Overall light intensity would still rely on the distance between the earth and the moon, which was in fact closer in 1893, 1912 and 1930.

It also turns out that the nearest approach made by the earth and moon to the sun does not in fact happen for another two weeks, long after the full moon has waned.

Jacqueline Mitton, of the Royal Astronomical Society, said she could not explain how the brightest moon myth could have gained credence. "About the only noticeable effect would have been a higher lunar tide. I suppose it is a good example of millennial madness; and what better time than when it's a full Moon?" she said.

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