Irradiation by cosmic ions plays a relevant role in the “space weathering” of solid materials in the airless bodies (rocky and/or icy objects) in the Solar System. Here, I discuss about some of the effects that have been studied in “simulation” experiments with a view to their astrophysical relevance. In particular I review some experimental results obtained so far after irradiation of relevant materials, namely: sputtering, ion implantation, and chemical synthesis of molecular species different from the original ones. All of those effects are accomplished by changes in the optical properties of irradiated layers and then of the color of the surfaces of the airless bodies. Some specific examples of the application of the experimental results to the physics and chemistry of planetary surfaces are discussed as well.