If they all show a monotonic negative slope in these plots, the smooth terrains of the Moon, Mars and Mercury differ by other different terrains on a same planetary body. This is particularly obvious for the Moon where MDS curves for both Highlands and Mare terrains seem to converge at short baseline (100 m) to a value of 0.5–0.81. This is also true for Mars and Mercury but because such low baselines are not available, the MDS values for younger terrains never reach the ones of older terrains.