2009 goes out on a blue moon

New Year’s Eve celebrations were a bit brighter this year with a blue moon shining in the sky Thursday night.

A blue moon -- the second full moon in a month -- isn’t really uncommon, occurring on average every 2 1/2 years. But “on New Year’s Eve it is very rare,” said Scott Kardel, a spokesman for the Palomar Observatory in San Diego County. The last one was in 1990.

The name is a bit misleading -- the moon does not appear blue. Rather, the name refers to the expression “once in a blue moon.”

Though many stargazers probably watched the skies on New Year’s Eve, most astronomers don’t like full moons because they make the sky too bright, Kardel said.


“But a full moon is convenient if you’re out celebrating,” he said.