Abstract
<jats:p>Saturn exhibits numerous unique anomalies: the composition and age controversy of its main ring system (tens to hundreds of millions of years vs. billions of years), axial tilt of 26.7°, internal excess heat flux (~2.5 times absorbed solar energy), a nearly perfectly axisymmetric magnetic field (offset <1°), the persistent north-polar hexagonal wave, JWST-discovered "black pearls" and asymmetric star-arms, irregular satellite populations with anomalous orbits, the hemispheric dichotomy of Iapetus, and a rotation-rate variation cycle driven by an internal "planetary heat pump." Existing models address these anomalies independently, lacking a unified trigger. This paper proposes that approximately 65 million years ago, a fragment swarm—derived from the disrupted Fifth Planet—carrying icy-rocky debris and metallic particles, swept through the Saturn system at a relative velocity of ~20 km/s, with a flyby distance of approximately 2–3 Saturn radii (~120,000–180,000 km). This single flyby event triggered a multi-stage evolutionary chain: (1) The instantaneous gravitational tidal torque altered Saturn's axial tilt to 26.7°, providing an external trigger for the "lost satellite" (Chrysalis) hypothesis; (2) Gravitational perturbation sent an icy satellite into the Roche limit, where it was tidally disrupted, forming the young, pure-water-ice main rings with an inclination inherited from the perturbed satellite's orbital plane; (3) Tidal friction injected substantial heat into Saturn's interior, partly explaining its excess heat flux and potentially reactivating helium rain sedimentation; (4) The dynamo layer was disrupted, resetting the magnetic field to a nearly axisymmetric state; (5) A portion of the fragment swarm was captured by Saturn's gravity, forming the irregular satellite population; (6) Asymmetric impact of dark carbonaceous material on Iapetus's leading hemisphere produced its distinctive dichromatic appearance; (7) External energy injection coupled with Saturn's internal "planetary heat pump" supplies energy for the hexagonal wave and the JWST-discovered "black pearls/asymmetric star-arms"; (8) The flyby perturbed Saturn's internal stratification, influencing the rotation-rate feedback cycle driven by auroral heating.</jats:p>