The European Space Agency just revealed a sound that human ears were never meant to hear: the voice of a cosmic horror buried deep inside our planet.

Beneath our feet, the ceaseless roiling of molten iron and nickel in Earth’s outer core powers a planet-sized electromagnet. It’s an unseen, unheard presence that’s always around us. And since 2013, three ESA satellites, called the Swarm mission, have recorded its electromagnetic activity all over the planet, from the depths of the core to the edges of space.

Fair warning: This is the part of the horror movie where someone decides to go ahead and read the ancient text — the one written in blood on parchment that was probably made from human skin — out loud. Except that this is real life and instead of the Necronomicon, we get a super-cool blend of art and science. But it’s basically the same thing, and if playing this recording summons an elder god into your living room, resurrects a cursed pharaoh, or at least startles your cat a little, don’t say we didn’t warn you.

Sound waves, light waves, and the signals from a planet-sized electromagnet all share the same basic physics: they can be described in terms of their wavelength, frequency, and other properties. That’s how a team of scientists and musicians at the Technical University of Denmark doomed us all translated Swarm’s recordings into sound waves.

“The team used data from ESA’s Swarm satellites, as well as other sources, and used these magnetic signals to manipulate and control a sonic representation of the core field,” explains Technical University of Denmark geophysicist and musician Klaus Nielsen in a statement. “The rumbling of Earth’s magnetic field is accompanied by a representation of a geomagnetic storm that resulted from a solar flare on 3 November 2011.”

The result is the spookiest sound we’ve ever heard, and it’s just in time for Halloween.

It sounds a little the creaks and groans of a ship in rough seas, but at times it almost sounds like voices growling (you’re safest not to listen too closely to those; don’t ask us how we know).

The only thing spookier would than that sound would be a much louder version of that sound, filling the air around you, coming from dozens of directions at once. And if you’re in Copenhagen, Denmark this week, you’re in for a terrifying treat.

“We gained access to a very interesting sound system consisting of over 30 loudspeakers dug into the ground at the Solbjerg Square in Copenhagen,” Nielsen says. “We have set it up so that each speaker represents a different location on Earth and demonstrates how our magnetic field has fluctuated over the last 100,000 years.” The speakers will play the eldritch voice of our planet at 8 a.m., 1 p.m., and 7 p.m., local time from October 24 to October 30.

“This project has certainly been a rewarding exercise in bringing art and science together,” says Nielsen.

And if you play it backward, you can hear a chorus of demonic voices chanting all of Sam Neill’s lines from Event Horizon — probably.