Combining all transit spectroscopy data sets available from the optical to the near-infrared (NIR) for one of the most iconic exoplanets, the hot Jupiter HD189733b, reveals the dominance of scattering by aerosols layers, above which a damped water band arises in the NIR and the sodium doublet reaches high altitudes in the thermosphere, as seen in the optical. Only high thermospheric temperatures (up to 10,000 K) or supersolar sodium abundance can explain the deep absorption in the cores of the sodium lines in the presence of aerosols. I will present the PyETA code for comparing synthetic transmission spectra to observations from different instruments (ground-based or space-borne, resolving powers from 10^2 to 10^5), which I employed to obtain these results. By using PyETA models, I will also illustrate a novel technique to characterize aerosols with simultaneous optical to near-infrared coverage of new generation, high-resolution spectrographs (GIARPS: HARPS-N + GIANO, CARMENES, ESPRESSO, …), which opens new perspectives for the characterization of exoplanetary atmospheres.