DETROIT (WWJ) – A celestial event is taking place on Friday that happens, well, once in a blue moon.

A full moon will be shining brightly on July 31 but this isn’t just any ordinary full moon. It’s known as a blue moon — the second full moon to appear within a single month, according to modern folklore. The first was on July 2.

Conditions should be ideal for viewing the blue moon Friday in metro Detroit, with forecasters calling for clear skies all night long.

Blue moons, which don’t actually appear to be the color blue, are rare occurrences. The last happened a few years ago on August 31, 2012, and the next won’t happen again until January 2018.

Despite it’s name, Friday’s blue moon will look pale gray and white. If the moon does appear to be unusually bluish, it could just be your eyes. Scientists say, although highly unlikely, that smoke and dust particles in the atmosphere could cast a tint on the moon.

Happy moon watching!