Once in a Blue Supermoon

Photo Credit: wichatsurin, istockphoto.com

You may have heard that this August will have a blue moon. The phrase “once in a blue moon” is a common idiom used to describe a rare or uncommon event. But what exactly is a blue moon, and just how rare is it?  

There are two types of blue moons: monthly and seasonal. A monthly blue moon is the second full moon to occur in one month. A seasonal blue moon is the third full moon in a season that has four full moons instead of the typical three. This August, we’ll see a monthly blue moon. 

What makes this blue moon unique is that it coincides with a supermoon. A supermoon (also known as a perigean full moon) refers to when the moon is at perigee, the closest point to Earth in its orbit. When the moon is at perigee, it appears both bigger and brighter than an average full moon. The combination of a supermoon with a blue moon is called a blue supermoon. While blue moons take place roughly every two and a half years, according to NASA, the next blue supermoon will not occur until 2032.  

The blue supermoon will take place on August 30th, and it will peak at 9:36 p.m. EST so make sure you don’t miss your chance for this “once in a blue supermoon event!”