Colour contrasts of lunar grounds

Four colour contrasts have been studied for 104 lunar regions between wavelengths 4000 Å and 8000 Å. Distinct colour differences are found. The greatest contrast between topographs occurs at longer wavelengths. The regional colour differences between the two short wavelengths 4035 Å and 5538 Å show a general trend of increasing reddening with age. For the other three colour differences (Delta (tfrac{{{text{4 7 6 5}}}}{{{text{7 9 2 2}}}}), Delta (tfrac{{{text{4 7 6 5}}}}{{{text{6 6 9 2}}}}) and Delta (tfrac{{{text{6 6 9 2}}}}{{{text{7 9 2 2}}}})) , a trend of variation with albedo is detected, and the less scatter on points for the colour differences above the wavelength 6000 Å.