Planetary mass-radius diagram showing the planets presented herein (blue circles), the Solar System giants (green diamonds) and the transiting exoplanets (red circles; data from TEPCat; masses measured by the radial-velocity technique to better than 20% precision). The dotted lines depict model planets of pure iron, rock and ice (from Fortney et al. 2007) and 3-Gyr isochrones for model planets with various H/He fractions that are irradiated by a Sun-like star at 0.045 AU (from Baraffe et al. 2008). The cyan rectangle indicates the notional transition region between ice giants and gas giants, where planetary mass is between twice that of Neptune and half that of Saturn.