GREENSBORO, N.C. — As the saying goes, "Once in a blue moon," these things don't happen all the time. This weekend, you'll have a chance to sneak a peek at a blue moon. But, it's different than what you'd think.

Come to find out, there are two types of blue moons: a traditional blue moon, and a "seasonal" blue moon. Let's break down the differences.

A traditional blue moon is pretty simple. It happens when you have two full moons during a single month. The second full moon is known as a "blue moon". 

Seasonal Blue Moon
Look up this weekend to see the full moon. It's the "Seasonal Blue Moon" - since there are four full moons this spring season.
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A "seasonal blue moon" looks at seasons rather than months. If there are four full moons in the same season, you can have a seasonal blue moon. The third full moon in that sequence is known as the seasonal full moon.

So, this weekend marks our third full moon in our Spring 2019 season. There will be one more full moon before we enter summer. 

Of course, a blue moon isn't actually blue -- that's just the term. It will look big and bright just like any other spectacular full moon should.

Both types of blue moons are rather rare. A traditional full moon is slightly more common, occurring once every 2.41 years. Compare that to a seasonal blue moon which happens just once every 2.68 years.