A major step forward in our understanding of the formation mechanism and evolution with cosmic time of galaxies is given by the recent development of powerful astronomical tools able to detect exceedingly faint signals from remote distances. One of the latter developments of particular signifcance was the opening of wavelengths longwards the classical visual band to the astronomical observation from space. From the mid '80 with the pioneering IRAS survey, until today, with the operation of the Herschel Space Observatory in the far-infrared and the Large Atacama Millimetre Array (ALMA) in the millimetre, a variety of initiatives have been put in operation to observe the Cosmo at long wavelengths. Among the many novelties emerging from all this, it became more and more evident the role of diffuse media in galaxies in shaping their spectral emission and modifying the flux emerging from stars.

Barbara Lo Faro, Graduated in the Faculty of Mathematical, Physical and Natural Sciences at the University of Padua.