Blue moons occur every 2.7 years on average. Friday is your last chance to see one until July 31, 2015. This Friday's full moon is known as a "blue moon," the second full moon in the calendar month.

Add Yahoo as a preferred source to see more of our stories on Google. When you buy through links on our articles, Future and its syndication partners may earn a commission. As we ready ourselves for ...

Tonight is the blue moon -- which isn't blue, of course, unless you happen to be near a volcano. It was actually a mistake by an amateur astronomer in Sky & Telescope magazine in 1946 that led to our ...

Value-conscious sky watchers can rejoice Monday as the night could bring into focus a rare two-for-one: a supermoon and a seasonal blue moon converged for a single viewing. NASA says that combination ...

Add Yahoo as a preferred source to see more of our stories on Google. A view of the full moon, known as the "Super Blue Moon" or "Super Sturgeon Moon," as it reaches perigee — the point of closest ...