“That only happens once in a blue moon.”
It’s a common phrase, but we actually get our fair share of blue moons this year. But just what is a blue moon? When there are two full moons that happen in a single calendar month, the second full moon is called a blue moon.
How often does that happen? Usually we experience one every two to three years. But 2018 is different – we have two blue moons this year. The first is on Jan. 31 (the first full moon was on Jan. 1). We’ll get another blue moon on March 31.