Coevolution of moons and the spin axis of their host planet – Melaine Saillenfest (IMCCE, Observatoire de Paris)


Aula Seminari, Dipartimento di Matematica


Satellites alter the spin-axis precession rate of their host planet. The tidal migration of moons is therefore an efficient driver of resonance crossing between the spin-axis and orbital precession modes of a planet. Once the planet is captured in a so-called “secular spin-orbit resonance”, the migration of its moons produces a large obliquity increase over billions of years. The system, however, converges towards a highly unstable configuration. This mechanism has direct applications in the solar system: Jupiter today is about to begin the tilting phase, Saturn is probably halfway in, and Uranus may have completed the final unstable stage.

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