This episode was originally written & produced by Kevin Edds.
What happens when we leave Earth's thin blanket of atmosphere, and what do other planets sound like? In this special episode, we have completely remixed one of our favorite shows! It's been re-written, re-edited, re-narrated, has new music, and even some new additional content. If you've heard the original, you'll definitely want to check out this remixed and remastered version. Featuring Dr. Lori Glaze, Dr. Keith Noll, and Dr. Scott Guzewich from NASA’s Goddard Space Flight Center.
MUSIC FEATURED IN THIS EPISODE
Sleep Walker by Dexter Britain
Where Were You When the World Was Made by Dustin Lau
Aura by Kollen
Quill by Future of Forestry
12:41 AM by Hotel Neon
Our Sky by One Hundred Years
Green by Eric Kinny
Dreams feat. Eebee by Generdyn
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View Transcript ▶︎
You’re listening to Twenty Thousand Hertz. I’m Dallas Taylor.
One of the most common questions I get is “what is my favorite episode of TTH?” ...and after a little thinking I always come back to the Space episode. Not necessarily for it’s sound design or production value, but rather for the subtext of the show… and was meant to communicate.
This episode was written to help illustrate that we’re all humans and we’re tied to this Earth. ...and our sense of hearing is proof. We’re united under a razor thin blanket of atmosphere on a space rock flying through the universe. Essentially, despite all the noise here on Earth, we’re all in this together.
Because our whole team loved the episode so much, we’ve decided to not just re-play it. But we’ve completely re-written it. We’ve even re-edited, re-narrated, and even changed out much of the music. For lack of a better term, this episode is a remix and remaster of one of our earliest and favorite episodes. If you remember it, you’ll love this fresh new take… and if you never heard the original episode, you’re in for a real treat.
Ok, here we go.
The best marketing tagline in movie history came from the Ridley Scott film, Alien: "In Space, no one can hear you scream." That phrase is true and not only because of the distance from Earth. It has to do with how sound travels.
Lori: You don't have sound in space because sound requires molecules.
That’s Dr. Lori Glaze, from NASA’s Goddard Space Flight Center. Lori oversees about 300 scientists that study all the planets and small bodies of our solar system.
Lori: You have to be able to move the molecules with the sound waves, and without the molecules there, the sound just doesn't move. You can try and use your lungs to push the sound out of your mouth but it won't travel anywhere.
That tagline from Alien I mentioned earlier, no one actually heard that either... as it was never read as voiceover in the trailer. It was just text, silent text, perhaps meant to imitate the specific science that explains how sound travels… or how it doesn’t travel.
Keith: My name is Keith Noll. I am the chief of the planetary systems lab at Goddard Space Flight Center. I think I've studied almost every planet or satellite in the solar system that has an atmosphere.
Sound as we think about it could be vastly different in other places in our solar system. Keith has some ideas on how other planets might sound to our ears..
Keith: What is sound? It's the vibrations of molecules in the air [SFX]. It's a pressure wave. Of course sound can be transmitted through any kind of physical medium. If you are in a swimming pool [SFX] you can still hear sound. That's being transmitted through water. Earthquakes [SFX] are essentially sound waves being transmitted through the solid earth.
Sound takes on many forms but the kind we're most familiar with is pressure waves moving through gas.
The most common example of how different gasses affect your vocal cords is the old party trick of breathing in a helium balloon.
As the gasses, you're pushing it back out of your lungs over your vocal cords, [SFX: play example] because the density is lower, the vibration frequencies end up being higher and that's why you sound like Mickey Mouse.
Let’s go from planet to planet in our solar system to find out what each surface would sound like. To our ears. To be clear though, you’d pretty much die instantly everywhere, except for here. But, for these examples we’re going to pretend to have superhuman powers that will keep us alive. So, with that disclaimer out of the way, let’s start closest to the sun.
Lori: Places like… Mercury and these rocky bodies with no atmospheres would be similar to being in space. There would not be much sound if any.
Keith: Mercury is an airless body, so we're back to listening for Mercury quakes [SFX], essentially. That would be really the only source of sound.
And you could only hear these Mercury quakes if your head was pressed up against the rock [SFX], because there’s no atmosphere for traditional sound to travel through.
Next up, Venus.
Lori: In my mind, what sound would be like on the surface, because you have this really dense atmosphere, much denser than Earth's, the sound would be more like or tend toward what things sound like when you're underwater [SFX].
If you could imagine something in between air and water [SFX], that kind of density, you're running your hand through that and you would feel that [SFX].
If you were to just materialize on the surface in that environment of 900 degrees Fahrenheit and a hundred times our atmospheric pressure, you would first be crushed [SFX] and then you would probably just burn up completely [SFX].
Keith: One thing we do know about Venus is that is has lightning, so you might hear thunder [SFX].
I wonder what other things, like my voice, might sound like. [SFX] I’m on Venus in this ethereal world that’s a mix between a gas-like atmosphere and water. I’m almost floating, but yet it’s not as restrictive as being submerged in water.
My voice… The thunder… [SFX]. It’s all slightly muffled and distorted as it travels through the thick atmosphere.
[SFX: Earth - forest sounds]
Now we’re home: Earth. We’re not going to stay here for long, but it’s worth mentioning the amazing diversity of sound on our planet. The sandy deserts [SFX]… lush forests [SFX]… the sound of the ocean [SFX], both on the surface [SFX]… and below [SFX]. It’s a rich soundscape, because our ears are perfectly in tune with it… More on that later.
Now Mars. And here’s where it gets interesting since Mars has been the subject of so much fascination for thousands of years. It’s one of the best places where life might have, or could exist.
Lori: Sound on Mars is going to be the opposite direction of Venus because the atmosphere on Mars is very, very thin compared to Earth's so there's just not very many molecules and sound requires molecules.
Countless movies have been made about Mars, including the Hollywood mega-hit The Martian, starring a stranded astronaut portrayed by Matt Damon.
Keith: Loved the movie. It was fun to watch, but it's not the Mars we know, it's a very different Mars.
[SFX: The Martian soundbite]
So the real Mars isn't anything like that, but Mars does have an atmosphere, albeit a thin one.
So that storm scene wasn’t quite accurate.
Keith: You wouldn’t necessarily hear the wind itself… You would hear the dust that's being picked up [SFX] and it would be banging against the faceplate of your spacesuit.
Scott: So I enjoyed that movie a lot, but the atmosphere as it was shown was not scientifically right.
That’s Scott Guzewich, a Research Astrophysicist at NASA.
Scott: Basically, the problem with what you saw in the movie there where the atmosphere is so thick that it's picking up boulders [SFX] and knocking things over. It's just not possible. I mean the wind speed can get very high, as high as hurricane force at the surface sometimes.
So imagine a hundred mile per hour wind on Earth, if you're standing in a hurricane, obviously you'd be almost blown off your feet.
If you were standing on the surface there in Mars and you put your hand out [SFX] in that hundred mile per hour wind, you would feel it, but it would feel like a gentle breeze here on the surface of Earth.
That sounds pretty cool. Standing in a hurricane but it only feels like a soft wind. But without a spacesuit, you’d die pretty quickly right?
Scott: You wouldn't die instantaneously but you'd want to be getting into shelter as fast as possible. First, the atmospheric pressure is dramatically lower than it is here on the surface of Earth. So, all the water in your body would attempt to boil, basically, instantaneously [SFX]. The water covering your eye, the water in your mouth, and even the water in your cells and your blood. That wouldn't kill you right away but it would be very uncomfortable immediately. You could probably survive for a few tens of seconds, maybe a minute. You could potentially get a very rapid dose to frostbite on your entire body [SFX]. Again, you wouldn't necessarily die right away, but it'd be quick.
And how about sound. What could we expect to hear?
Scott: Our ears aren't really designed to work in that sort of very near vacuum sort of atmosphere. So we wouldn't hear too much, maybe if you were scuffling along on the surface, you could maybe very faintly [SFX] hear that sound as you were clawing at the ground and gasping for air [SFX].
The temperature obviously is colder in general, so that drives a lower speed of sound, and it seems that a lower speed of sound would tend to lower the pitch [SFX], make your voice sound deeper… but then the atmospheric density would kind of go to raise your pitch, so it seems like the pitch probably balances out.
If voices won’t carry far, how about a piano?
Scott: The very high-pitched, high frequency noise at the far right end of the piano, you probably wouldn't hear that at all, but maybe the deepest bass sounds that the piano makes [SFX], you might be able to just pick those up with a microphone if it was sensitive enough.
So we’ve explored the first four planets of our solar system, and learned some of the ways their unique atmospheres and conditions shape their soundscape, or lack thereof. We’ll continue our exploration of sound to the outer reaches of our solar system, after the break.
We now know what the planets of our inner solar system would sound like to our ears. Let’s move on to Jupiter.
What’s interesting is that Jupiter doesn’t have a solid surface. Hard to imagine but the whole planet is made up of gas. And that just keeps getting denser and denser—eventually becoming a liquid the closer you get to its core. The pressure and temperature variations are what cause those beautiful swirling bands.
Keith: So the interesting thing on Jupiter is that the pressure and the temperatures where the cloud decks are, are actually not so inhospitable.
So what are cloud decks?
Keith: So you've got these very distinct cloud layers in Jupiter's atmosphere. So y’know, it's just fun to imagine. What would it sound like? Would you get these echos?... because you have these super powerful lightning bolts, more powerful than anything on the Earth, so you'd have really, really loud thunder [SFX]. You'd hear echoes of echoes of echoes [SFX] just back and forth. It's fun to think about.
So how about the rest of the outer planets?
Keith: Jupiter and Saturn, I think you could consider to be pretty similar. Uranus and Neptune are pretty similar to each other. So all four atmospheres are primarily hydrogen and helium.
So it sounds like if you tried to speak on any of them your voice would be higher?
Keith: I think so, cause the atmosphere is 75% hydrogen which is even less dense than helium and the rest is helium. I think we'd all be Mickey Mouse on Jupiter and Saturn.
And what about our old friend Pluto? Anything different?
Keith: It is probably the thinnest bound atmosphere that we know. But, it also looks really complex. It's got layers. It's pretty different. Mainly because the temperature is so low. Nitrogen there is an ice. Carbon monoxide is mostly an ice. That's probably the weirdest, most different kind of place in terms of thinking about how composition, temperature, pressure would affect the sound.
We’ve covered the planets and acknowledged our old friend Pluto, and it’s becoming clear that detecting sounds throughout our solar system is pretty difficult. So why is it so easy for us here on Earth?
Keith: Our ears are good for a very specific environment. They've evolved. Once you take them out of that they're probably not exactly the tool you would want. If you built an audio receiver and sent it to all these places… What could you hear that the human ear could hear, and more interestingly, what could you hear that the human ear would never be able to hear?
That's what I want to know.
Surprisingly, we have never recorded another planet with a traditional microphone.
Scott: There is going to be a microphone on the next Mars Rover. The rover launched in 2020, it's supposed to have a microphone on it. We expect that it'll hear a few different things. The sound as the rover drives [SFX] across the surface for example, will be transmitted both through the atmosphere and through the body of the rover itself. You should be able to hear the wheels kind of crunch [SFX] along on the sand and on the rocks [SFX].
While the next Mars Rover will have a traditional microphone on it, NASA’s Insight Lander was recently able to pick up sound waves through the air using it’s seismometer. The seismometer, which is designed to measure marsquakes, was able to pick up these low vibrations up to 50Hz. Unless you have particularly bassy speakers, you may not be able to hear the low rumble, but here’s what those vibrations sounds like...
[Play unaltered clip]
And for those of you who couldn’t hear anything, here’s what that clips sounds like pitched up two octaves...
[Play pitched up clip]
We’re so accustomed on Earth to hearing sound associated with what we see. But in true outer space no one can hear a titanic supernova explosion, or a hurtling asteroid smash into the moon, or even… hear you scream.
Lori: How rare is sound in the known universe? It's pretty rare. Even just in our known solar system, places like the moon and Mercury and these rocky bodies with no atmospheres would be similar to being in space. There would not be much sound, if any.
When we think of Earth as special in terms of being able to even support life, it goes much further than that. It’s one of the true places in the universe where sound is abundant and has impacted that life on an evolutionary level.
Scott: If you look at life on Earth, being able to hear something seems to be a very big advantage biologically right? From very simple animal species, there is a benefit to being able to hear sound. Because you can become aware of either predators, or prey, or food sources. So if I were to really get out my speculation hat, y’know alien life in the universe would probably have an advantage to hear things also... in whatever planet or ocean or atmosphere they lived in.
However, these aliens might perceive sound in a completely different way, a way that’s in tune with their own environment, and perhaps hear completely different frequencies.
When you think of space, it’s mostly… space. Where no medium exists to transport sound. Yet, it’s perfect for… light. Light fills the universe, but sound does not.
Keith: The whole universe is connected by light. Light anywhere in the universe can travel to anywhere else in the universe, but with sound you really are truly in different islands of sound and they're all isolated because they're all stuck in this space that doesn't transmit sound. It transmits light perfectly well but not sound.
Sound as we perceive and understand it, is so unbelievably rare, but it’s abundant right here, where we are, within this thin blanket of atmosphere. But if we travel straight up, it goes away very quickly. It gets quieter, and quieter [sfx]… until it’s gone.
Twenty Thousand Hertz is produced out of the studios of Defacto Sound, a sound design team dedicated to making television, film, and games sound insanely cool. Find out more at defactosound.com
This episode was produced and edited by Kevin Edds.
With help from Sam Schneble.
It was edited, sound designed and mixed by Colin DeVarney.
We’d like to thank Dr. Lori Glaze, Dr. Keith Noll, and Dr. Scott Guzewich for speaking with us.
We’d also like to thank Elizabeth Zubritsky, Aries Keck, Nancy Jones, Richard Melnick, and Kevin Hartnett at NASA’s Goddard Space Flight Center.
Finally, you can chat with me and the rest of the 20k team through our website, facebook, twitter or by writing hi @ 20k dot org. We love hearing from you, so don’t be shy. Thanks for listening.