Once in a Blue Moon

Ever here of the saying, "Once in a blue moon." Well 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. Depending on where you live will determine if the moon will "appear" blue...it's not really the color.

If it's cold enough, and ice crystals form in the atmosphere, then the reflection of the light will illuminate a "ring" around the moon, which may glow blue.

The first full moon occurred on Dec. 2. and the second full moon will occur on Thursday in time for the New Year's countdown. We east coasters will see the moon directly above us and it's going to be absolutely brilliant.

The New Year's Eve blue moon will be visible to us here in the United States and those in Canada, Europe, South America and Africa. For you folks down under, the full moon will show up on New Year's Day, making January a blue moon month for you.

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.

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.[source]

"Blue moons have no astronomical significance", said Greg Laughlin, an astronomer at the University of California, Santa Cruz. Furthermore he says, "'Blue moon' is just a name in the same sense as a `hunter's moon' or a `harvest moon'."

I find it very significant in light of the reports from an Australian and Israeli scientist who have discovered and identified ancient light-sensitive genes, known as a cryptochromes, that occur in corals, fish and humans which are responsible for triggering the annual mass spawning of Great Barrier Reef corals that follows a full moon.

Reporting in the journal Science, team leader Oren Levy said that the Cry2 gene, stimulated by the faint blue light of the full moon, appears to play a central role in triggering the mass coral spawning event, one of nature's wonders. "This is the key to one of the central mysteries of coral reefs. We have always wondered how corals without eyes can detect moonlight and get the precise hour of the right couple of days each year to spawn," added co-researcher Ove Hoegh-Guldberg.

Exposing corals to different colors and intensities of light and sampling live corals on reefs around the time of the full moon, Levy found the Cry2 gene at its most active in Acropora corals during full moon nights.

"We think these genes developed in primitive life forms in the Precambrian, more than 500 million years ago, as a way of sensing light."

"The fact they are linked with the system that repairs damage from ultraviolet radiation suggests they may evolved in eyeless creatures which needed to avoid high daytime UV by living deep in the water, but still needed to sense the blue light shed by the moon to synchronize their body clocks and breeding cycles."

The researchers believe that the genes are, in a sense, the functional forerunners of eyes. In humans, cryptochromes still operate as part of the circadian system that tunes us to the rhythms of our planet, though their light-sensing function appears lost to us.

"Many of these genes developed in deep time, in the earliest phases of organized life on the planet,"  "They were preserved for hundreds of millions of years before being inherited by corals when they developed about 240 million years ago, and are still found today in modern animals and humans. They are an indicator that corals and humans are in fact distant relatives, sharing a common ancestor way back." -Bill Leggat

The Cry2 gene (cryptochromes genes) stimulated by the faint blue light of the full moon appears to play a central role in triggering the mass synchronized coral spawning, and can even affect humans.

The researchers were shy about speculating whether humans are in some way affected by the full moon, but they did acknowledge that cryptochromes probably still play a part in our body clock.[read more]

So if your skies are clear and your out celebrating the new year, remember to take a peek at this "once in a blue moon" appearance, and enjoy the brilliant orb as it rises over the skyline.

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