The logarithm of the surface acceleration as a function of planetary radius (log-g diagram) for Earth-like exoplanets (green curve) corresponding to planetary sizes of 1−2 R_⊕. To define boundaries and illustrate the calculated trends, the expected log-g for homogeneous, self-compressible spheres of iron, silicate, and high-pressure water ice have been added as dashed lines. The black diamond represents the position of the Earth. The crosses denote the relative position of CoRoT-7b (C3) and Kepler-10b (K1), respectively, and indicate their observational uncertainties.