There is no sound in space. Sound is produced by the vibration of molecules; any time something moves, it causes a corresponding vibration in its medium -- whether water or air -- which, in turn, vibrates the eardrum of any nearby listeners and is perceived as sound. In the vacuum of space, there is no air -- nothing for vibrations to travel through -- which means there is no way for those vibrations to reach your ears. In space, truly, no one can hear you scream. That does not mean that we have no audio recordings of what's out there; quite the contrary. But they are not originally recorded as audio. Rather, they are changes in energy, picked up by instruments on various probes: plasma vibrations, electromagnetic disturbances, radio waves, and the interactions of charged particles. These recordings can then be converted into sounds, much like the terrestrial radio signals -- also a kind of electromagnetic radiation -- we create to communicate and entertain. Unlike tuning in to your favourite radio program, though, the sounds of space are a whole lot stranger: the howls and whistles of radiation, lightning, plasma waves, coronal mass ejections, solar winds. Listen to more via CNET.