What does a moon sound like?

SARAH MCCAMMON, HOST:

What does a moon sound like? If it's one of Jupiter's moons, maybe something like this

(SOUNDBITE OF ELECTROMAGNETIC WAVES)

A MARTÍNEZ, HOST:

Almost like those old dial-up modems, right? A NASA space probe called Juno captured this when it flew past Ganymede earlier this year. Ganymede is actually the largest moon in the solar system. It's even bigger than the planet Mercury.

SCOTT BOLTON: It's the only moon in the solar system that has a magnetic field, its own magnetic field. Not even every planet really has that.

MCCAMMON: That's Scott Bolton, the principal investigator for the Juno mission. And what you're actually hearing on that recording...

(SOUNDBITE OF ELECTROMAGNETIC WAVES)

MCCAMMON: All those beeps and blurps (ph) are radio and plasma waves in the moon's magnetic field picked up by special equipment. The data was converted to audio, so we could all hear it.

BOLTON: I just love the idea that you can listen to a body. And it's screaming at you. In this case, Ganymede's screaming, I have my own magnetic field. That's a very special tale because it's the only moon that's like that that we've discovered. And it puts it in its own category, really.

MARTÍNEZ: This is just the beginning of their research into what those waves mean. The NASA researchers now plan to fly Juno past two of Jupiter's other moons to get even more data and possibly more sounds.

(SOUNDBITE OF JACOO'S "TOWARDS THE LIGHT") Transcript provided by NPR, Copyright NPR.