Scale-length fitted to the surface-brightness profiles from UV to sub-mm and normalized with respect to r₂₅, h/r₂₅, as a function of wavelength for the galaxy NGC 5457 (M 101). The scale-lengths of mass (of dust, gas, and stars) and SFR surface-density profiles and the scale-length of U profile, normalized with respect to r₂₅, are plotted as horizontal lines because they are not associated with a wavelength. They and the corresponding error bars are drawn at λ = 2000μm.