Editing Planetary core (section)

===Dynamo===
[[Dynamo theory]] is a proposed mechanism to explain how celestial bodies like the Earth generate magnetic fields. The presence or lack of a magnetic field can help constrain the dynamics of a planetary core. Refer to [[Earth's magnetic field]] for further details. A dynamo requires a source of thermal and/or compositional buoyancy as a driving force.<ref name="Hauck and Van Orman 2011" /> Thermal buoyancy from a cooling core alone cannot drive the necessary convection as indicated by modelling, thus compositional buoyancy (from [[Phase transition|changes of phase]]) is required. On Earth the buoyancy is derived from [[crystallization]] of the inner core (which can occur as a result of temperature). Examples of compositional buoyancy include precipitation of iron alloys onto the inner core and liquid immiscibility both, which could influence convection both positively and negatively depending on ambient temperatures and pressures associated with the host-body.<ref name="Hauck and Van Orman 2011" /> Other celestial bodies that exhibit magnetic fields are Mercury, Jupiter, Ganymede, and Saturn.<ref name="Pollack, et al. 1977" />