Equator-anchored cosine fit results for maria reflectance vs. wavelength. (a) Coefficient of determination (R²) indicating goodness of fit to the SZA-motivated model ﹩R(| \,\rm{lat}\,| )={R}_{\,\rm{eq}\,}+A(\cos | \,\rm{lat}\,| -1)﹩. (b) Normalized amplitude A/R_eq representing the fractional reflectance change from the equator to higher latitudes. NUV–NIR wavelengths (321–1548 nm) show A < 0 (increasing reflectance with increasing latitude), while Lyα (121.6 nm) shows A > 0 (decreasing reflectance with increasing latitude), both consistent with enhanced weathering at equatorial latitudes.