Key properties of the Earth’s core through time. (a) and (b) The temperature and heat flows of the core and CMB secularly decrease with time. (c) Once the interior has sufficiently cooled, the inner core rapidly solidifies at ∼4 Gyr. (d) The thermal buoyancy flux of the core gradually decreases as the core cools. Once the inner core solidifies and exsolves light elements, the compositional changes inject energy into the outer core and boost the overall core buoyancy flux. (e) and (f) The late energy increase in the outer core due to inner-core solidification causes coinciding discontinuities in the magnetic moment and the magnetopause radius. On all plots where applicable, dots represent measurements of PIE (4.5 Gyr) properties with uncertainties.