Is There Sound In Space?
QUICK ANSWER
Mostly no. Sound requires a medium like air, water, or any material to propagate, and most of space is essentially a vacuum. However, in regions with enough gas (like galaxy clusters), sound waves can travel. NASA detected pressure waves from the Perseus cluster's black hole, which were later sonified into audible audio.
The common saying that 'in space, no one can hear you scream' is true for most of space. Sound is a vibration that travels through a material medium, and most of space is essentially empty. But in regions where enough gas exists (like galaxy clusters), sound waves can travel through the gas, even if there's no air. Space is mostly silent, but not entirely.
Why can't you hear in space?
Because sound needs a medium. Sound is a wave of compression and rarefaction traveling through matter, whether air, water, or solid material. Without enough particles to vibrate, there's no sound to be heard. Most of space contains so few particles per cubic meter that sound waves can't propagate at all. Earth's atmosphere, by contrast, has trillions of trillions of molecules per cubic meter, providing plenty of medium for sound waves. The vacuum of space is one of its most fundamental features.
How thin is the space between stars?
Vastly thinner than any Earthbound vacuum we can produce. The interstellar medium has roughly 1 atom per cubic centimeter on average. By comparison, Earth's atmosphere at sea level has about 10^19 (10 billion billion) molecules per cubic centimeter. Even the best vacuum chambers on Earth have about 10^7 molecules per cubic centimeter, still vastly denser than interstellar space. Sound simply can't travel meaningfully through medium so thin. Astronauts on EVAs hear nothing from outside their suits.
Are there places with sound in space?
Yes, where there's enough gas. Galaxy clusters contain enormous amounts of hot gas, sometimes hundreds of times Earth's atmospheric density at the centers. Sound waves can propagate through this gas. Stellar atmospheres also support sound waves. NASA's Chandra X-ray Observatory detected pressure waves from the supermassive black hole at the center of the Perseus galaxy cluster, propagating through the cluster's hot gas. These are real sound waves, just at frequencies far below human hearing.
Can we hear space through other methods?
Yes, through sonification. NASA has translated various astronomical signals into audible sound by scaling their frequencies up by many octaves. The Perseus cluster sound waves released in 2022 went viral after NASA scaled the original frequencies up 57 octaves into human hearing range. Radio waves from pulsars can be turned into audible clicks. These aren't direct recordings (sound can't travel across the vacuum to us), but translations of real astronomical data into sound we can experience.
Space is mostly silent because most of it is a vacuum, and sound needs a medium to travel through. But in places with enough gas (galaxy clusters and stellar atmospheres), sound waves can propagate. NASA has even captured sound waves from a supermassive black hole. Most of space is silent, but not all of it. The popular image of complete cosmic silence is mostly but not entirely accurate.
More Space Basics Questions
Mystery Question?
Mystery Question?
Mystery Question?