KOSCIUSKO — Tonight, eyes will turn to the sky to witness an event that happens only once in a blue moon — literally.

According to the National Aeronautics and Space Administration website, a blue moon does not appear blue. Rather, the colorful nickname has been attached to the second full moon to occur within a calendar month, something that does not occur too often.

This month’s previous full moon happened on Wednesday, July 1. According to earthsky.org, the last blue moon occurred on Aug. 31, 2012.

NASA’s website goes on to say that, on occasion, the moon can appear blue, however, this usually requires a volcanic eruption filling the atmosphere with ash, which acts as a color filter.