Blue moon time, date: Space oddity comes once in a blue moon Friday evening

It's not blue, it's not all that rare, and its cosmic significance is nil.

But it could prove problematic for werewolves.

When the fat old moon climbs out of the sea and into the sky at 7:36 Friday evening, it will be the second full moon of the month. Such an occurrence, which happens every 2.7 years, is called the blue moon, a designation whose origin is more mysterious than the phenomenon itself.

A calendrical, not celestial, quirk is the reason. Twelve full moons occur each year, about 29 days apart. A typical month is 31 days, so occasionally two full moons squeeze into one month, usually at the beginning and the end. August's first full moon appeared on Aug. 1.

The term blue moon means a rare event or long period of time. But the moon really only turns blue when it's colored by cobalt particles from erupting volcanos or forest fires.

The next one will occur in July 2015. While the event is meaningless to astronomers, it may yet afford lovers the opportunity to get twice as romantic.