Mars music. Or at least audio by Mars. As in the planet.

Earlier this week, NASA announced that scientists have been detecting a lot more seismic activity on Mars than they thought the planet was capable of generating.

The InSight lander started hearing these sounds soon after it took up residence on Mars in November 2018. As it registered marsquakes, it also picked up a background hum from the planet.

Mars hums? Apparently it’s a combination of the thin Mars wind and whatever geological movement is going on below the surface. Either that or it’s Martians in their subterranean cities.

It’s far too low for human ears, but you can retune things so we can hear what this Martian song sounds like. Listen here.