Why can't you hear the sound of an exploding meteor?

Atoms of many gases exist in space, but they are not concentrated enough to provide a breathable atmosphere (air). "Air" refers to an atmosphere, a collection of gases, which can only exist around a semi-massive object in space, one that has both enough mass to have forceful gravity, and a magnetic field of sorts to prevent the "solar wind" from stripping the atmosphere (air) away. For example: Mars has decent mass with enough gravity to contain an atmosphere on its surface, but lacks a strong magnetic field. Therefore the solar wind (high energy particles from the Sun) strips most of the air from the planet. The atmosphere of Mars is consequently much less dense than Earth's.