Mutual Gravitational Capture as a Mechanism for Planetary Growth: An Alternative Hypothesis

This study proposes a new hypothesis for the growth of rocky planets through successive events of mutual gravitational capture followed by planetary fusion. The model suggests that collisions resulting from mutual gravitational captures within the Hill sphere occur under initial conditions of zero relative velocity, aligned velocity vectors, and relatively similar mass ratios. Under these parameters, the model predicts that collisions would occur at velocities allowing the complete fusion of the bodies and the formation of structures at multiple scales. The resulting planetary mass would contain merged inner cores, mantle heterogeneities, mountain chains, continental blocks, and surface redistribution of minerals. Some of these signatures may be associated with magnetic anomalies, hotspots, mantle transition zones, subducted crust, and mass extinction events. The hypothesis also provides new parameters for simulations of satellite capture and comet ejection during earlier stages, when planets were less massive, enabling testable predictions for future studies on Earth’s evolution. Keywords: life evolution planetary evolution, planetesimals, orbital dynamics, satellite capture, mantle heterogeneities, core evolution, tectonics.