"Black moon" has many confusing definitions in astronomy, witchcraft and pop culture

By Alex Heigl
Updated September 28, 2016 02:00 PM
Credit: Roberto Machado Noa/LightRocket via Getty Images

No, that weird term in your social media feeds isn’t a Norwegian metal band’s new album. A rare lunar event called a “black moon” – something that hasn’t happened since March 2014 – will occur in the Western Hemisphere on Sept. 30.

“Black moon” can mean a variety of things – more on that in a minute – but the common usage, and the definition in this case, is the second new moon in a given calendar month. It’s the inverse of the more well-known (and sung about) “blue moon,” or the second full moon in a given calendar month.

Regrettably, it will not be a visible event, because by the very definition of a new moon, the side of the moon illuminated will be facing away from the Earth.

The timing is also super-confusing. “It’s the second new moon this month in all of the Americas, but not in Europe and points east from there,” astronomer Bob Berman told Accuweather. Because the black moon will occur at 8:11 p.m. Eastern Time – after midnight across the pond – areas in the Eastern hemisphere will “officially” experience it on Oct. 1.

The Eastern Hemisphere, however, will be treated to another black moon around Halloween, which is super-metal and a very good time to schedule that séance you’ve been putting off.

The waters (and the skies) get murkier here, to mix metaphors. Another definition of black moon means that there are no new moons in a month, and as Berman adds, “The phrase could also mean the third new moon when there are four in a season, which is actually also one of the definitions of a blue moon when the same thing happens to a full moon.”

Black Moon is also the name of an American hip hop group, whose debut album Enta da Stage was released in 1993. The use the phrase as an acronym that means “Brothers who Lyrically Act and Combine Kickin Music Out On Nations,” so there’s that. (It’s also an album by Emerson, Lake & Palmer and a Black Sabbath song!)

Lastly – and most confusingly – according to Wikipedia (which, funnily enough, links this information out to something called “Witchipedia,” which then redirects back to Wikipedia), some Wiccans consider the black moon to be a special time that enhances the potency of spells and rituals, while others believe nothing magical should be performed during a black moon.