ORLANDO, Fla. – When it comes to the topic of a Blue Moon, you may have been living a lie.
The widely-known definition of a Blue Moon is two full moons in the same month. The last time that happened was in October 2020. The thing is, the full moon rising on Aug. 22 is the first full moon of the month. So how can this weekend’s full moon also be a Blue Moon?
According to Sky & Telescope, traditionally, a Blue Moon was not the second full moon in a month but occurs when there are four full moons in a season, rather than the typical three. This was published in the Maine Farmer’s Almanac during the 1930s. The Blue Moon, using the original definition, is the third full moon of the four in the same season.
In 1946, the original definition was misinterpreted by an amateur astronomer and the widely-known definition of two full moons in a calendar month was created.
The fourth full moon of the summer will occur on Sept. 20. The first day of fall or Autumnal Equinox happens on Sept. 22.
The time there will be four full moons in a season, and therefore true Blue Moon will occur in 2024.
The August full moon is also known as the Sturgeon Moon because the giant sturgeon on Lake Michigan and Lake Champlain were caught during this part of summer. The moon will technically be full at 8:02 a.m. Sunday but will appear full Saturday and Sunday night, weather permitting.
In both definitions of the Blue Moon, the moon does not actually appear blue.