Mass-radius diagram for all known planets with masses in the range 0.5–20 M_⊕ and radius 1–4 R_⊕, comprising Earth-like to super-Earth to sub-Neptune regimes. Data are taken from the TEPCat database (Southworth 2011). Planets belonging to multiple systems are marked as open gray dots while single planets are marked as solid gray dots. The four planets of the K2-285 system are marked in different colors. Theoretical models for the internal composition of the planets are taken from Zeng et al. (2016).