Top: planetary mass–radius diagram, including all known exoplanets with a radius and a mass constrained to a precision better than 12% (gray, open circles). GJ7 b is depicted by the red circle. Interior models of different compositions (Zeng et al. 2019) are shown by the solid colored lines. Two other planets discussed in the text are labeled. Bottom: planetary insolation plotted as a function of planetary radius for the same planets. The eight planets of the Solar System are shown as a reference. All axes are on a logarithmic scale.