LOS ANGELES – Once in a blue moon there is one on New Year's Eve. Revelers ringing in 2010 will be treated to a so-called blue moon. According to popular definition, a blue moon is the second full moon in a month. But don't expect it to be blue — the name has nothing to do with the color of our closest celestial neighbor.
A full moon occurred on Dec. 2. It will appear again on Thursday in time for the New Year's countdown.
"If you're in Times Square, you'll see the full moon right above you. It's going to be that brilliant," said Jack Horkheimer, director emeritus of the Miami Space Transit Planetarium and host of a weekly astronomy TV show.
The New Year's Eve blue moon will be visible in the United States, Canada, Europe, South America and Africa. For partygoers in Australia and Asia, the full moon does not show up until New Year's Day, making January a blue moon month for them.
However, the Eastern Hemisphere can celebrate with a partial lunar eclipse on New Year's Eve when part of the moon enters the Earth's shadow. The eclipse will not be visible in the Americas.
A full moon occurs every 29.5 days, and most years have 12. On average, an extra full moon in a month — a blue moon — occurs every 2.5 years. The last time there was a lunar double take was in May 2007. New Year's Eve blue moons are rarer, occurring every 19 years. The last time was in 1990; the next one won't come again until 2028.
Blue moons have no astronomical significance, said Greg Laughlin, an astronomer at the University of California, Santa Cruz.
"`Blue moon' is just a name in the same sense as a `hunter's moon' or a `harvest moon,'" Laughlin said in an e-mail.
The popular definition of blue moon came about after a writer for Sky & Telescope magazine in 1946 misinterpreted the Maine Farmer's Almanac and labeled a blue moon as the second full moon in a month. In fact, the almanac defined a blue moon as the third full moon in a season with four full moons, not the usual three.
Though Sky & Telescope corrected the error decades later, the definition caught on. For purists, however, this New Year's Eve full moon doesn't even qualify as a blue moon. It's just the first full moon of the winter season.
In a tongue-in-cheek essay posted on the magazine's Web site this week, senior contributing editor Kelly Beatty wrote: "If skies are clear when I'm out celebrating, I'll take a peek at that brilliant orb as it rises over the Boston skyline to see if it's an icy shade of blue. Or maybe I'll just howl."

Source: http://news.yahoo.com/s/ap/20091230/..._sci_blue_moon

For New Year’s revelers in the Western hemisphere, the calendar will not quite have turned into the new decade when the perfectly round orb lights up the night sky.

Not since 1990 has the world had the opportunity to observe on a mass scale the compounded impact of a Blue Moon and bubbly.

The double full moon phenomenon happens on average every 2.7 years, with the most recent in May 2007, and the next set for August 2012.This month, the moon was also at its maximum on December 2.

Why Blue? For no particular reason, according to Space.com, a popular science website based in the United States.

“If there's been a recent volcanic eruption that poured significant ash into the upper atmosphere, it is possible for the moon to take on a blue tint,”noted the site's editorial director Robert Roy Britt.

“That's not expected tonight,” he added, as if by way of apology.It also turns out that the term “blue moon” is a misnomer that can be traced back to an editorial blooper 65 years ago in the normally irreproachable magazine Sky and Telescope.

The original meaning was the third full moon in a season with four, a more common occurrence.There is also a cocktail — curacao, gin and a twist — by that name, and a turn of the (20th) century expression meaning something absurd.—AFP