Rapid falling of an orbiting moon to its parent planet due to tidal-seismic resonance

Abstract

Tidal forces play an important role in the evolution of the planet-moon systems. The tidal force of a moon can excite seismic waves in the planet it is orbiting. A tidal-seismic resonance is expected when a tidal force frequency matches a free-oscillation frequency of the planet. Here we show that when the moon is close to the planet, the tidal-seismic resonance can cause large-amplitude seismic waves, which can change the shape of the planet and in turn, exert a negative torque on the moon causing it to fall rapidly toward the planet. We postulate that the tidal-seismic resonance may be an important mechanism, which can accelerate the planet accretion process. On the other hand, the tidal-seismic resonance effect can also be used to interrogate the planet’s interior by long term tracking of the orbital change of the moon.