Exoplanet Ring Dynamics: Shepherd Moon Resonances (2D)

This 2D top-down companion replaces the 3D original's decorative particle-field shader with the actual physics its title implies: a ring of particles on real Kepler orbits (a = -GM·r/|r|³) around a planet, perturbed by a shepherd moon whose gravity opens resonance gaps at radii where T_particle/T_moon is a simple ratio like 2:1 or 3:2 — the same Kirkwood-gap mechanism that shapes Saturn's rings and the asteroid belt. Drag the moon-mass and moon-orbit sliders and watch gaps open and close at the computed resonance radii in real time.