A “once in a blue moon” phenomenon will happen on Wednesday, August 30, 2023. It will be a specifically special celestial event; a super blue moon. This is the first blue supermoon since December 2009.

What is a blue moon? Usually, a normal calendar month has one full moon. From time to time, an extra full moon will sneak in. A blue moon happens once every two to three years, or seven times in the Metonic Cycle of 19 years. (The 19-year lunar cycle is what the Greek Calendar was based on.)

What is a supermoon? A supermoon is when the moon appears unusually large in the night sky. This phenomenon is also known as Perigee when the moon’s orbit is closest to Earth. A supermoon occurs three to four times a year.

What is a blue supermoon or a super blue moon? When a second full moon of a month is at its closest approach to Earth, we see a super blue moon. This is a super rare phenomenon, which according to NASA, won’t happen again until January or March of 2037, 14 years from now!

There is another weather phenomenon making this supermoon extra interesting, Hurricane Idalia. The moon controls the tide, and when the moon is closest the tide is the highest. The higher tides, also known as king tides, occur during new moons and full moons when the gravitational pull is highest from the sun and moon pulling in the same direction on Earth.

The combination of Idalia’s dangerous storm surge partnered with the king tides, people living and visiting along the Florida coast should stay alert for beach erosion and coastal flooding.