Measured values for core mass fraction (dotted line), FeO mass fraction in the mantle (dashed line) and the total iron contents (black circles) of Vesta (Va), Mars (Ma), Earth (Ea), Venus (Ve) and the Sun. All these measurements come with uncertainties that are not plotted here; references for the data are given in the main text. The measured core mass fraction clearly increases with increasing mass, while the measured FeO mantle fraction decreases accordingly.