Very rarely. Almost never. “Once in a blue moon.”
The idiom denotes something that happens hardly ever. Yet blue moons are more than a figure of speech, as this month of August is about to prove.
August has graced us, gloriously, with one full moon already, the Sturgeon Moon. The month will soon offer an encore—a remarkable second full moon, known in folklore as a “blue moon.” It will be made even better, as it’s a supermoon. The largest of the year.
It’s no technical term, blue moon. Nor are they necessarily blue-colored—though they can be. Rather, the term arose from folklore.
As for supermoons, while they sound larger than life, they too exist, occurring because of the moon’s irregular orbit around Earth.
We will dig into both these moons.
Here’s what you need to know about August 2023’s rich lunar offerings later this month.
What’s in a Blue Moon?
Here, we are dealing not with exact science, but folklore. “Blue moon” has disparate definitions, as folks are disparate creatures. And “lore” is—well, just that. There are several accepted definitions of a blue moon today.
Firstly, the calendrical classification is what features this month. Those didn’t exist prior to 1946. Just as the name implies, calendrical blue moons denote the calendar month. When two full moons occur in one month, the second is a blue moon. They don’t happen every month—or every year—but they do happen.
Secondly, the seasonal blue moon is the older, more deeply-ensconced definition, with more historical clout. This is when four full moons fall within the solstice and equinox during the year—that is, within a season. There are typically three full moons per season. But when a seasonal blue moon occurs, there are four. Contrary to expectation, the third—not the fourth—is the blue moon.
Thirdly, blue moons don’t have to be blue, yet the term sometimes denotes color. Nor do blue-colored moons have to be full. According to EarthSky, these happen when smoke is present in Earth’s atmosphere. When smoke particles are slightly wider than 900 nanometers, such as when a wildfire is raging nearby, they can scatter red light very efficiently, resulting in a moon with a cool-tinted hue.
By Michael Wing
