Revelers ushering in the New Year of 2010 in many parts of the world will be treated with a so-called "blue moon" -- the second full moon in a month if the skies are clear.
The term blue moon has nothing to do with the color of the moon. The name reflects the relative rarity of two full moons in a month and is linked to the saying "once in a blue moon."
Most years on average have 12 full moons, with one appearing each month. 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 a blue moon appeared on New Year's Eve was in 1990, and it won't happen again until 2028.
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.
xinhua
(Agencies)
