Why doesn't sound travel in space?

Sound is really a vibration. When something vibrates, it shakes the air particles next to it. This vibration passes from one particle to the next until it reaches our ears, and that is how we hear sound. So sound needs a carrier, like air, water, or a solid object, to travel.

Space, though, is almost completely empty. There is no air there, because space is a 'vacuum' — an empty area with very little matter in it. Since there are no particles to carry the vibration, sound cannot travel through space.

That's why the explosion sounds and roars we hear in space movies aren't actually real. Astronauts use special radios to talk to each other. A radio turns sound into invisible electric and magnetic waves, and these waves can travel even without air.