Blue Super Moon? Here's how to better understand the Moon's nicknames
Last week, an out-of-the-ordinary cosmic event unfolded – a phenomenon that hadn't graced our skies since 2009 and won't return until 2037. Infrequent as it may be, don't worry if you happened to miss it. The catchy name aside, blue super moons are not that spectacular.
Unlike the “blood” moon, when the moon actually turns red during a lunar eclipse, the label "blue" moon is deceiving. A blood moon occurs when the moon goes behind the Earth's shadow. The moon doesn’t disappear completely, though, because some sunlight gets bent by the Earth's atmosphere. The sunlight is actually made up of all colors, but the blue part gets scattered by tiny particles in our atmosphere (which is why the sky looks blue). This leaves only red light to hit the moon, making it look red.
In contrast, a blue moon isn't blue at all; its name simply denotes the second full moon within a single calendar month – and it’s as silvery as usual.
Because a month spans around 30 days, while the moon completes its orbit in 29.5 days, the difference accumulates, occasionally leading to two full moons in one month. Back in 2018, we witnessed a "blue blood moon," and no, this isn't an aristocratic lunar entity or celestial nobility. It refers to a lunar eclipse coinciding with the second full moon of the month.
As for the “super”, yes, a supermoon does appear larger than the typical full moon, but the difference isn't monumental. To put it in perspective, the increase is roughly 7% – akin to the difference between a 16-inch and 17-inch pizza. And even though it's larger, we don't call a 17-inch pizza a "super-pizza." This change in apparent size isn't indicative of a change in the moon's physical dimensions either. Instead, it arises from the moon's proximity to Earth in its elliptical orbit. The point nearest to Earth is dubbed the "perigee". Conversely, the farthest point is known as the "apogee." A supermoon occurs when the full moon happens at perigee.
That's what's behind the concept of a "blue super-moon": the second full moon in a calendar month that coincides with the moon's nearest approach to Earth. It might not actually be blue, and the "super" part isn't as grand as it might seem. Nevertheless, it's a pretty captivating sight.
You might have come across some other interesting names for full moons too, like the “Harvest” Moon, “Pink” Moon, or “Strawberry” Moon, names that gained popularity thanks to the Sky and Telescope magazine in the 1940s.
Let's take a quick tour through the months: January gets its "Wolf Moon" name from the howling wolves in the winter plains. The "Snow Moon" graces February, in line with it being the coldest month in the northern hemisphere. As March arrives and the weather warms, we welcome the "Worm Moon." In April, the "Pink Moon" takes its name from the return of vegetation to the prairies. May's "Flower Moon" celebrates the full bloom of spring. June brings the "Strawberry Moon" as strawberries ripen. July is known as the "Buck Moon," linked to buck's antler growth. August's "Sturgeon Moon" coincides with the time when sturgeon fish are easily caught in the Great Lakes. The most famous of the nicknames is the "Harvest Moon" of September, close to the Fall equinox, marking the last major harvest before winter. October's "Hunter's Moon" highlights the transition from harvesting to hunting for food.
November's "Beaver's Moon" suggests a time to burrow for winter, and December's "Cold Moon" captures the chilly days of the winter solstice. These poetic names underscore that few astronomical bodies have captivated human imagination so thoroughly as our celestial companion. Night after night, against a starry canvas, the moon graces our sky with radiant embrace. So, while the upcoming "blue super moon" might not be assensational as it sounds, it's a reminder of the fascinating mysteries of the firmament. As you gaze up at the night sky, let it serve as a testament to the incredible wonders that the universe has to offer, even in seemingly routine events.
Wladimir Lyra is an associate professor of astronomy at New Mexico State University. He can be reached at wlyra@nmsu.edu (email) or @LyraKstellation (twitter).
This article originally appeared on Las Cruces Sun-News: Blue Super Moon? Here's how to better understand the Moon's nicknames
