Get ready for Blue Moon

excerpt from EarthSky.Org ( http://earthsky.org/astronomy-essentials/full-moon-names) There are usually three full moons in between an equinox and a solstice, or vice versa. Seven times in 19 years, four full moons fall in a single season. In that case, the third of a season’s four full moons is also called a Blue Moon. The next Blue Moon by this definition will happen on August 21, 2013.