Is there sound in space? The answer will surprise you
Space is silent… or is it? Physics has an answer that completely breaks common sense.
Is there sound in space?
It depends on what you call “sound.”
If you want to know if humans can hear in space, the answer is no — sound waves need a medium (air, water) to propagate, and the vacuum doesn’t have one.
But here’s the plot twist: space is not a total vacuum.
There is matter there, just ultra-spaced out. And with the right instruments, scientists can capture “sounds” that our ears would never detect.
For example: NASA has already recorded the “sound” of black holes, Jupiter’s auroras, and solar storms.
And that’s what I need to write about — because the classic answer (“there is no sound in space”) is correct… but incomplete.
The classic answer: “In space, no one can hear you scream”
This phrase comes from the movie Alien (1979), and it is technically correct.
Sound is vibration. When you speak, your vocal cords make the air vibrate. These vibrations travel through the air to someone’s ear.
Without air (or another medium), no vibration. No vibration, no sound.
The problem: Space is a vacuum — the absence of air.
So if you scream in space, your vocal cords will vibrate, but there is nothing to transmit that vibration. It’s like clapping underwater with thick gloves — the movement exists, but it doesn’t generate audible sound.
That’s why they say: “there is no sound in space.”
And for a long time, I accepted this as an absolute truth.
The plot twist: vacuum ≠ nothing
This is where it gets interesting.
When people say “the vacuum of space,” we imagine nothing. Zero. Total emptiness.
But it’s not quite like that.
Space has matter
Interstellar space has, on average, 1 atom per cubic centimeter.
Does it seem like nothing? It is. But it’s not zero.
To compare:
- Air on Earth: ~10^19 molecules per cm³ (trillions of trillions)
- Interstellar space: ~1 atom per cm³
- Laboratory vacuum: ~10^6 molecules per cm³
In other words: the “vacuum” of space is much emptier than any vacuum we can create on Earth.
But there is still something.
How “sound” exists in space (but you can’t hear it)
Okay, there is matter in space. But 1 atom per cm³ is too little to transmit audible sound, right?
Correct.
But there are other types of “sound” that don’t depend on high density.
1. Plasma waves
Plasma is the fourth state of matter (solid, liquid, gas, plasma). It’s gas so hot that electrons separate from atoms.
Space is full of plasma — especially near stars, planets with magnetospheres, and black holes.
And plasma can vibrate. These vibrations are technically sound waves, but at frequencies that humans cannot hear (very low, like 57 octaves below middle C).
2. “Translated” electromagnetic waves
NASA uses a technique called sonification: it takes electromagnetic waves (radio, X-rays) and converts them into audible frequencies.
Examples:
- M87 Black Hole: NASA converted X-ray waves into sound. The result? A deep, haunting “howl.”
- Jupiter’s Auroras: Converted radio waves sound like something out of a space horror movie.
- Solar Wind: Plasma vibrations from the sun captured by probes.
Technically it’s not “sound” in the traditional sense. But it is detectable vibration that can be translated into something our ears understand.
So, is there sound in space or not?
It depends on the definition.
If “sound” = waves that humans hear:
No. The vacuum is too thin to transmit audible frequencies.
If “sound” = mechanical vibrations propagating in a material medium:
Yes. Plasma waves, vibrations in gas clouds, magnetic oscillations — all of these exist.
If “sound” = scientific data converted to audio:
Yes. NASA, ESA, and other agencies do this all the time.
The point is: vacuum is not absolute absence. It’s just enough absence to prevent audible sound.
Questions I had (and the answers)
“So can astronauts communicate in space?”
Not without radio. Even if you scream inside your helmet, the sound doesn’t cross the vacuum. That’s why they use radio wave communication.
“How does NASA record these ‘sounds’?”
Instruments capture electromagnetic waves (radio, X-rays) or plasma vibrations and convert them into frequencies we can hear. It’s “translation,” not direct recording.
“Is there anywhere in space where you could hear sound?”
Inside ships, space stations, or planetary atmospheres (like Venus, which has a dense atmosphere). But in the interstellar vacuum? No.
“Is the vacuum really ‘empty’?”
No. There is always something — atoms, particles, radiation. A perfect vacuum (absolute zero) is theoretically impossible.
Why this fascinates me
Because it shows how definitions matter.
For years, I repeated that “there is no sound in space” as if it were an absolute truth. And technically it’s right — if you’re talking about audible sound.
But when you expand the definition (mechanical waves, plasma vibrations, data sonification), space becomes much less silent than it seems.
And it reminds me that many “absolute truths” are just truths within a specific context.
Space is not mute. We just don’t have the ears to listen to it.
💡 Summary in 3 points:
- Audible sound needs a dense medium (air, water) — the vacuum of space doesn’t have enough density.
- But space is not empty: it has plasma, spaced-out gas, and particles that can vibrate.
- Scientists capture plasma and electromagnetic waves and convert them into sound we can hear.
Did you enjoy discovering that the answer isn’t so simple? I’ve written about other physics concepts that seem obvious but have more nuances. Check out the post on Why the sky is blue — it’s about how the color of the sky isn’t exactly what it seems.
References:
-
NASA: Sounds of the Universe nasa.gov
-
Space.com: Can you hear sounds in space? space.com
-
Physics Stack Exchange: Sound propagation in space physics.stackexchange.com
Personal note: I want to study more about plasma waves and exactly how the instruments that capture these vibrations work. And also explore the difference between quantum vacuum and classical vacuum — apparently even “emptiness” has quantum fluctuations. Saving that for another post.