CINCINNATI (WKRC/WKEF) – A Blue Moon will illuminate the night sky this weekend, but this one is, by definition, different than the last one we had on Halloween 2020. Spoiler alert — the moon still won’t appear blue. A Blue Moon actually has a couple of definitions. The most used is the second full moon to occur during a single month. But, the Blue Moon this weekend will be a seasonal one. What is a seasonal Blue Moon?