Fig. 18. Dependence of Spectrum Slope on Solar Incidence Angle.

All on-planet spectra are shown. The sharp increase in the slope of daytime Callisto spectra towards the terminator (90^o solar incidence), and sharp reduction of slope once on the night side, is well seen. Ganymede and Europa do not show this effect. All the steep Ganymede spectra are near the south pole (Fig. 10).
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