Blue moon to light up the night sky this week

http://www.space.com/16841-full-moon-why-does-it-happen-how-does-it-affect-us-video.html

Skywatchers should circle Aug. 31 on their calendars, for the date offers the last chance to see a so-called "blue moon" for nearly three years.

 

The moon reaches its full phase at 9:58 a.m. EDT (1358 GMT) Friday, marking the second full moon of August (the previous one occurred Aug. 1). Stargazers won't be able to see two full moons in a single month again until July 2015.

 

Friday's full moon won't actually be blue, unless a load of dust or ash in the atmosphere lends it that particular hue from your vantage point. In any event, blue moons aren't named for their color, and they look like any other full moon in the sky most of the time.

 

Rather, the term has always been associated with an "extra" full moon. In the first half of the 20th century, for example, it apparently referred to the third full moon of a season — spring, summer, winter or fall — that boasted four full moons instead of the usual three.

 

But that definition was misinterpreted over the years, and today we call the second full moon in a single month a "blue moon."

 

http://www.mnn.com/earth-matters/space/stories/blue-moon-to-light-up-the-night-sky-this-week