Is There Such a Thing as a Planet Sound?

Image of the Week for Voyager Squashes View of Solar System
This artists rendering depicts Voyager 2 spacecraft as it studied the outer limits of the heliosphere--a magnetic bubble around the solar system that is created by the solar wind. Data from Voyager was used to make samples of what it might sound like if you could hear the passage through the boundary. NASA

Can a planet make a sound? In a sense, it can, although no planet that we know of has a sound-emitting similar to our voices. But, they do give off radiation, and that can be used to make sounds we can hear.

Everything in the universe gives off radiation that — if our ears were sensitive to it — we could "hear". For example, people have captured emissions given off when charged particles from the Sun encounter our planet's magnetic field.

The signals are at really high frequencies that our ears can't perceive. But, the signals can be slowed down enough to allow us to hear them. They sound eerie and weird, but those whistlers and cracks and pops and hums are just some of the many "songs" of Earth. Or, to be more specific, from Earth's magnetic field. 

In the 1990s, NASA explored the idea that emissions from other planets could be captured and processed so we could hear them. The resulting "music" is a collection of eerie, spooky sounds. You can listen to a good sampling of them on NASA's Youtube Site. However, since sound can't travel through empty space (that is, there's no air there to vibrate so we can hear things), how do these songs even exist? It turns out, they're artificial depictions of real events.

It All Began With Voyager

The creation of "planetary sound" started when the Voyager 2 spacecraft swept past Jupiter, Saturn and Uranus from 1979-89  The probe picked up electromagnetic disturbances and charged particle fluxes, not actual sound.

Charged particles (either bouncing off the planets from the Sun or produced by the planets themselves) travel in the space, usually kept in check by the planets' magnetospheres. Also, radio waves (again either reflected waves or produced by processes on the planets themselves) get trapped by the immense strength of a planet's magnetic field.

The electromagnetic waves and charged particles were measured by the probe and the data from those measurements were then sent back to Earth for analysis.

One interesting example was the so-called "Saturn kilometric radiation".  It's a low-frequency radio emission, so it's actually lower than we can hear. It is produced as electrons move along magnetic field lines, and they're somehow related to auroral activity at the poles. At the time of the Voyager 2 flyby of Saturn, the scientists working with the planetary radio astronomy instrument detected this radiation, speeded it up and made a "song" that people could hear. 

How Did Data Become Sound?

In these days, when most people understand that data is simply a collection of ones and zeroes, the idea of turning data into music isn't such a wild idea. After all, the music we listen to on streaming services or our iPhones or personal players is all simply encoded data. Our music players reassemble the data back into sound waves that we can hear. 

In the Voyager 2 data, none of the measurements themselves were of actual sound waves. However, many of the electromagnetic wave and particle oscillation frequencies could be translated into sound in the same way that our personal music players take data and turn it into sound.

 All NASA had to do was to take the data accumulated by the ​Voyager probe and convert it into sound waves. That's where the "songs" of distant planets come originate; as data from a spacecraft.

Are We Really "Hearing" a Planet Sound?

Not exactly. When you listen to the NASA recordings, you are not hearing directly what a planet would sound like if you were orbiting it. The planets don't sing pretty music when spaceships fly by. But, they do give off emissions that Voyager, New Horizons, Cassini, Galileo and other probes can sample, gather, and transmit back to Earth. The music gets created as the scientists process the data to make it so that we can hear it. 

However, each planet does have its own unique "song". That's because each one has different frequencies that are emitted (due to different amounts of charged particles flying around and because of the various magnetic field strengths in our solar system).

Every planet sound will be different, and so will the space around it. 

Astronomers have also converted data from spacecraft crossing the "boundary" of the solar system (called the heliopause) and turned that into sound as well. It's not associated with any planet but does show that signals can come from many places in space. Turning them into songs we can hear is a way of experiencing the universe with more than one sense. 

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Millis, John P., Ph.D. "Is There Such a Thing as a Planet Sound?" ThoughtCo, Oct. 24, 2017, thoughtco.com/is-there-such-a-thing-as-a-planet-sound-3073443. Millis, John P., Ph.D. (2017, October 24). Is There Such a Thing as a Planet Sound? Retrieved from https://www.thoughtco.com/is-there-such-a-thing-as-a-planet-sound-3073443 Millis, John P., Ph.D. "Is There Such a Thing as a Planet Sound?" ThoughtCo. https://www.thoughtco.com/is-there-such-a-thing-as-a-planet-sound-3073443 (accessed January 16, 2018).