Does sound travel faster in space?

Category: Space
Published: February 14, 2013

Sound does not travel at all in space. The vacuum of outer space has essentially zero air. Because sound is just vibrating air, space has no air to vibrate and therefore no sound. If you are sitting in a space ship and another space ship explodes, you would hear nothing. Exploding bombs, crashing asteroids, supernovas, and burning planets would similarly be silent in space. In a space ship, you could of course hear the other passengers because your ship is filled with air. Additionally, a living human will always be able to hear himself talk, breath, and circulate blood, because the air in his space suit which sustains his life also transmits sound. But two astronauts in space suits floating around in space will not be able to talk to each other directly no matter how hard they yell, even if they are only inches away. Their inability to talk directly is not caused by their helmets getting in the way, but is rather caused by the vacuum of space not carrying sound at all. That is why space suits are equipped with two-way radio communicators. Radio is a form of electromagnetic radiation just like light and can therefore travel through the vacuum of space just fine. The astronaut's transmitter converts the sound waveform to a radio waveform and sends the radio waves through space to the other astronaut, where is it converted back to sound for the other human to hear. I suspect the entertainment industry portrays this principle incorrectly on purpose for dramatic effect. A silent exploding space ship is not as dramatic as a booming one.

Public Domain Image, source: NASA.

Christopher S. Baird is a physics professor at West Texas A&M University and author of the book, The Top 50 Science Questions with Surprising Answers.

Topics: air, sound, sound in space, space movie, speed of sound, vacuum