Scattering, absorption, and emission of electromagnetic radiation occurs in practically all systems of matter and radiation. The measurement, observation, and theoretical modeling of this interaction provides information about the system’s physical and chemical properties down to length scales of a fraction of the wavelength. In the project, numerical methods and experiments are developed for scattering and emission by media of cosmic and terrestrial particles. Astronomical observations are carried out for Mercury with the NOT (Nordic Optical Telescope). The new and existing observations of Mercury and particulate terrestrial samples, with emphasis on icy samples, are interpreted using models and experiments. The project culminates, in preparation for the ESA/JAXA BepiColombo mission, in the synoptic interpretation of X-ray fluorescence emission spectra as well as ultraviolet, visible, and near-infrared reflection spectra and images of Mercury obtained by the NASA MESSENGER mission.