An easy way to grab someone’s attention is by telling them that something is different about the Moon. The Moon, you see, is our night sun, and thus holds an important place in our minds and hearts.
That being said, the “black moon” or “black supermoon” currently generating headlines is an embarrassingly bad concept that upsets me immensely.
First off, what is a “black moon?” Great question. This is how news outlets have apparently decided to rebrand the new moon, a moon phase where the Moon isn’t visible from Earth, when it occurs twice in one month. A supermoon, as you may know, is what we call it when the Moon’s cyclically-changing orbit brings it closest to Earth, making it appear slightly larger in the night sky.
Thus a “black supermoon” is a new moon that would appear slightly bigger in the sky, if you could see it, which you can’t.
While we’re at it, we might as well review some elementary school science. The Moon orbits Earth approximately every 28 days. During that time, it goes through a series of “phases,” what we call it when the side of the Moon illuminated by the Sun is oriented differently towards Earth. The full moon occurs when the Moon is on the opposite side of the Earth from the Sun, so we see its entire illuminated face. Quarter moons occur when only half of the moon’s face is illuminated. (The name makes more sense if you think of the moon as an orb instead of a disk.) The previously mentioned new moons occur when the Moon is on the same side of the Earth as the Sun.
It’s worth emphasising that you cannot see the new moon at night. That isn’t because it’s black for some reason, but because it has set and is not in the night sky. If you have a sensitive enough camera, you might be able to see a sliver of the new moon during the day or around sunrise and sunset.
For thousands of years, humans have used the Moon as a way to keep track of the passage of time. But the number of times the Moon orbits Earth doesn’t cleanly align with the duration of a single orbit around the Sun, so its phases don’t fit cleanly into our calendar. That means that sometimes you might have more full moons than usual during a season or even during a month. You might also have more new moons (or quarter moons) during a season or a month.
The term “blue moon” was coined to describe the extra full moons. It’s not standardised, but almanacs (those folksy pseudoscience sources) used to refer to a season with an extra full moon as having a blue moon, with the moniker going specifically to the third full moon. Later, blue moon came to refer to the second full moon in a calendar month with two of them.
In recent years, there’s been a deluge of stories featuring weird moon names like “super blood wolf moon“ ” names that might rack up Facebook shares, but don’t mean much of anything. Recognising these stories’ enormous popularity, even more (ostensibly) fact-focused media outlets like CNN end up writing about them.
And thus, “black moon” was born, a click-y term popularised by astrologers not recognised by actual scientists. I will acknowledge that there are cultures that have different names for the Moon, and sometimes people claim that the moon names popularised online originate from Native Americans. But as far as we’ve been able to tell, the terms that the National Enquirer or the Daily Mail use for the Moon are not related to these names.
So what is a black supermoon? It’s nothing of importance. The Moon has been orbiting the Earth for around 4.5 billion years, and it remains unchanged aside from the occasional asteroid strike. It’s just the Moon. Our regular, old Moon really is amazing, though, and I encourage you to look at it.
But I also encourage you to think critically, fight the forces of pseudoscience and fake news that have permeated popular culture, and think before sharing an article ascribing wacky names to the lunar phases.