According to modern folklore, when there are two Full Moons in a month, we call the second a Blue Moon. Question: what do you call it when there are two New Moons in a month?
It's about to happen. On Dec. 31st, New Year's Eve, the moon will be new for the second time this month. (The first time was Dec. 1st.) Double new moons occur about once every 2.5 years, the same frequency as Blue Moons.
For more info on the various types of moons and a really cool picture gallery of Auroras (aka Northern Lights) visit SpaceWeather.com