Full moon, Blue Moon, Last Eclipse of 2009

This is the second full moon in December for the Americas, Europe, Africa, and far-western Asia. And according to recent tradition, a second full moon in a calendar month has the name Blue Moon.

Will December 2009 have a Blue Moon?

Any time you see the moon near the horizon, it can have a reddish color. The reason the moon’s (or sun’s) light must pass through a greater thickness of atmosphere when rising or setting than when overhead. So any moon, full or not, may look reddish when seen near the horizon.

Moonset

Because the December full moon comes so early in the month, this month will have two full moons this year.

• First December full moon: December 1, 2009
• Second December full moon: December 30, 2009

Tonight’s moon, like any full moon, will be out all night long, lighting up the nighttime from dusk till dawn.

Side Note: What's a Blue Moon?

The second of two full moons to fall in a single calendar month is called a Blue Moon.