  We report the scaling behavior of the Earth and Venus over a wider range of
length scales than reported by previous researchers. All landscapes (not only
mountains) together follow a consistent scaling behavior, demonstrating a
crossover between highly correlated (smooth) behavior at short length scales
(with a scaling exponent $\alpha$=1) and self-affine behavior at long length
scales ($\alpha$=0.4). The self-affine behavior at long scales is achieved on
Earth above 10 km and on Venus above 50 km.
