A supermoon over Poland in 2015Reuters

“A super blue blood moon eclipse is coming.” “Something the United States hasn’t seen since 1866.” “Watch the moon turn blood-red in the sky.”

Reading some headlines this week, you might think the world is headed for some kind of apocalyptic event. What on Earth, er, what on the moon is a “super blue blood moon”?

The super blue blood moon is, in short, a really cool celestial event, a mix of phenomena that, for a brief time, make the moon appear different to us than it usually does on January 31.

It’s super because the moon is now at the closest spot to to Earth in the moon’s monthly orbit, a point known as a perigee.

It’s blue not because of its color, but because it’s the second full moon in a calendar month, a rarish occurrence—it happens once every few years—that’s responsible for the expression “once in a blue moon.”

And there’s blood in the name because this particular event is a total lunar eclipse. When the Earth, sun, and moon are in perfect alignment, the moon falls inside the Earth’s shadow. Some sunlight still manages to reach the moon, and as it passes through Earth’s atmosphere, air molecules filter out most of the blue light. What’s left, red light, casts a reddish hue on the lunar surface.

On Wednesday, all three phenomena align. To us here on Earth, if we’re in the best viewing spots on the planet and the weather’s good, the moon will appear less silvery gray and more orangey red.

So, there’s nothing scary about the super blue blood moon. There’s nothing scientific about the name, either, as Matt Simon in Wired thoroughly explains here. But the wording is catchy and click-y and, in recent years, widely used on the internet. NASA has leaned into it with press releases and dramatic videos bearing the foreboding name. (Our less dramatic neighbors to the north, at the Canadian Space Agency, have opted not to use the term in promotional materials.) The name has the potential for widespread appeal, and provides a way in for the average person to become interested in learning about some celestial alignments in our cosmic home.

That’s what Richard Nolle had in mind, when he coined the term “supermoon” in 1979.

“‘Perigee syzygy’ is something that the average sixth-grader can’t handle, and that’s the average reading capability of the American adult,” Nolle said, referring to the term for a full moon during the moon’s closest approach to the planet. “So I figured we needed something a little more euphonic.”

Nolle is an astrologer based in Tempe, Arizona, who has been writing about supermoons for years and says the moon, when it is at its nearest to Earth, can contribute and influence geophysical activity, like earthquakes and volcanoes, and affect human behavior.

The idea that moon phases correlate with seismic activity has been frequently debunked by scientific research, and astrology is not a science field (though, as my colleague Julie Beck wrote recently, it’s enjoying a bit of a renaissance among Millennials.)

Nolle is credited with coming up with the term “supermoon,” even by his field’s skeptics. He first used it in an article in Dell Horoscope, an astrology magazine whose website includes horoscopes and stock-market outlooks. He said he first became interested in learning about the moon’s terrestrial implications when he taught sailing for the U.S. Navy in the 1980s.

“When you’re sailing in and out of the Sebastian Inlet or anywhere on the Atlantic coast, you become extremely aware of the tides,” Nolle said. “Because depending on the keel of your boat, you may or may not be able to get through. Anytime you’ve got a high tide, and particularly a supermoon-amplified high tide, it’s really easy to get in and out of the channel.”

Nolle has written astrological predictions based on celestial alignments each year for decades. He said he first started noticing the term “supermoon” in popular and mainstream news reports in 2009. “I noticed that some meteorologists began using it,” he said. “Science writers began using it in their articles. Naturally, I was delighted.”

Nolle points to the 17th-century German researcher Johannes Kepler as comparable to his situation. Kepler published several papers on, among other topics, astrology, and he studied meteorological data, collected over many years, to support his theories. Nolle said astronomers ended up adopting some of Kepler’s terminology. Today, a NASA space observatory to find Earth-sized planets around other stars is named for him. Kepler, of course, was working during a time in scientific study where the distinction between astronomy and astrology was often blurred.

The lunar trifecta, or the super blue blood moon—cue The Twilight Zone theme song—will be visible in North and Central America around sunrise on Wednesday. In Asia, the Middle East, and Australia, the event will occur after sunset on January 31. Western Europe and most of Africa and South America won’t see it. NASA will livestream the event starting at 5:30 a.m. EST on January 31 here.

Here’s when to look up Monday morning, around the world:

NASA

And if you’re in the United States:

NASA

Nolle said he will observe the event a few miles from his home in Tempe, near a view of the Superstition Mountains. “It’s going to be quite some sight to see,” he said.

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