A Blue Moon is a relatively rare occurrence, but August’s Blue Moon will be even more unique.
If you’re a fan of stargazing or simply track phases of the moon on your calendar, you already know that August only has one full moon — on August 22. And about now, you’re wondering how August can have a Blue Moon if there’s only one full moon in the month.
The reason is that August’s full moon is a seasonal Blue Moon, rather than a calendar Blue Moon. Seasonal Blue Moons happen less frequently, making them even more uncommon. Keep reading below, and I’ll explain the difference.
Frequency Of Full Moons
Historically, there were 12 names for full moons — one for each month. August’s full moon, by the way, is Sturgeon Moon. It gets its name from fishing tribes because the large fish are easiest caught in August, The Farmers’ Almanac explains.
There are roughly 29.5 days between full moons, which makes it unusual for two full moons to occur in a month with 30 or 31 days. Indeed, an article in the August 1937 issue of the now-defunct Maine Farmer’s Almanac explained that the moon “usually comes full 12 times in a year, three times for each season,” a Space.com article recounts.
“Occasionally, however, there will come a year when there are 13 full moons during a year, not the usual 12,” the Maine Farmer’s Almanac article continued. “And that extra full moon also meant that one of the four seasons would contain four full moons instead of the usual three.”
The Maine Farmer’s Almanac article went on to call this extra full moon of a season a “Blue Moon” so the other full moons could occur at the proper times relative to the calendar year’s solstices and equinoxes.
Origin Of A Common Definition
The more popular definition of the Blue Moon — the second full moon of a month — is the result of a misunderstanding.
Here’s what happened. First, the author of an article in Sky & Telescope magazine in 1946 misinterpreted the Maine Farmer’s Almanac article, and instead, called the second full moon of a calendar month a Blue Moon, a Sky & Telescope article explains.
That article — and its Blue Moon definition — was then cited on the popular radio program StarDate on January 31, 1980, Sky & Telescope explains. Finally, the 1986 edition of the board game Trivial Pursuit used “The second full moon in a month” as the answer to the question “What is a Blue Moon?”
By then, that definition had been accepted into common parlance.
How To View The Moon
OK, here’s the fun part. The moon will become full on August 22, at 8:01 a.m. Eastern. It will appear full from Friday night to Monday morning, so there will be numerous viewing opportunities. You can find moonrise and moonset times for your local area here to help you determine the best time to look at the Full Moon.
Be sure to look for the Blue Moon. Timeanddate.com notes that the next seasonal Blue Moon won’t happen until August 19, 2024.
Pro Tip: To get the best views of the Blue Moon, you’ll want to be somewhere dark — far away from city lights. A map of dark places for optimal stargazing may be found here.
While you’re making plans to look at summer’s Blue Moon, be sure you also read “The 7 Most Incredible Stargazing Sites In The U.S.” and all of our stargazing coverage as well, including “NASA Says This Will Be The Best Meteor Shower Of 2021” and “Saturn, Jupiter Put On A Show In August, Here’s How You Can See Them.”