Gravity-Gradient Induced Rotation During Planetary Side Passes: A Refraction- Analogy Framework

This paper proposes a novel hypothesis for the origin of rotational motion in extended bodies passing near planetary gravitational fields. Unlike traditional explanations that attribute planetary rotation to angular momentum inherited during formation, this work explores the role of off axis gravitational gradients. When an object passes the side of a planet, gravitational forces act unevenly across its structure, producing torque that induces rotation. The mechanism is analogous to light refraction: light bends in a gradient medium, while rigid bodies rotate under gravitational stiffness. Analytical derivations and conceptual models suggest that this torque is significant for small bodies, spacecraft, and asteroids during close flybys, though negligible for planetary scale rotation. The framework provides a new lens for understanding spin changes in orbital dynamics and offers potential applications in spacecraft attitude control and asteroid flyby prediction.