Irradiation by cosmic ions plays a relevant role in the “space weathering” of solidmaterials in the airless bodies (rocky and/or icy objects) in the Solar System. Here, Idiscuss about some of the effects that have been studied in “simulation” experiments witha view to their astrophysical relevance. In particular I review some experimental resultsobtained so far after irradiation of relevant materials, namely: sputtering, ionimplantation, and chemical synthesis of molecular species different from the originalones. All of those effects are accomplished by changes in the optical properties ofirradiated layers and then of the color of the surfaces of the airless bodies. Somespecific examples of the application of the experimental results to the physics andchemistry of planetary surfaces are discussed as well.