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Q & A: Did you hear that? Neither did I.

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Most recent answer: 10/22/2007
Why is it impossible to hear the sounds spaceships make in space when you are in space? Explain more than the "obvious."
- Antwan Robinson (age 14)
Portsmouth Virginia United States

Sound is our brain interpreting vibrations of the air that is in our ears. A vibration is something moving back and forth or up and down. The air vibrations that we hear come from something moving air rapidly back and forth.
For example, I hear a car honk it's horn down the street because a mechanism in the car vibrated the air around it back and forth. That vibrating air caused the air that was around it to vibrate, and those vibrations moved outward until they got to my ear. The key to me hearing the car's horn is that everywhere between me and the car there is air to vibrate.
Now, if I was in outer space floating in a space suit outside my space ship, I would not hear anything if the ship's engines fired. That is because, although there is air in my helmet, and there is air in the ship, there is no air between me and the ship. Since there is no air, there is nothing to carry the vibrations. Vibrations like sound need something to move back and forth, or there is no sound. That is why you can't hear things in space.
This is not an entirely obvious fact, expecially since many of us have been fooled by Star Wars and Star Trek to think that a ship in space should make a "whoosh" noise whenever it goes past us.


(published on 10/22/2007)

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