The chemistry of interstellar space

Interstellar space is not empty, but contains gaseous and particulate matter that is concentrated into very large regions known as interstellar clouds. In the denser and cooler clouds, the gas is molecular and most of the molecules detected are organic in nature. The gas-phase molecules are synthesised from precursor atoms by rapid exothermic reactions in the gas and on the surfaces of tiny dust particles. Since dense interstellar clouds collapse to form stars and planetary systems, the molecules produced in the clouds may be eventually incorporated into solid bodies such as comets, meteors, and even planets.