December 31, 2009

Blue Moon Tonight


Tonight brings a second full Moon this month—
a so-called “blue Moon”—to adorn the final night of the year.

This full Moon is called the Long Nights Moon
by some Native American tribes.


What is a "Blue Moon"?

When there are two full Moons in a single month, the second is often called a “blue Moon.”
On average, a "blue Moon" occurs once every 2-1/2 to 3 years.

The expression seems to derive from the extremely rare, actually blue-tinged Moon caused by atmospheric layers of forest fire smoke or volcanic dust at just the right height and visual angle.