BLUE MOON ALERT: Columbia's Galeras volcano is spewing ash miles high into the atmosphere, and this could set the stage for a beautiful "Blue Moon."

Fine volcanic ash floating in the air has been known to act as a color-filter, transforming ordinary moonlight from silver to blue. It is often said that Blue Moons are mythical or absurd, but they are real, and one may appear over your part of the world this weekend.