Innermost Stable Circular Orbit · ISCO
unseel.com · r = 6GM/c² · marginal stability · the plunge
Orbit r — GM/c²
Radial ω
phase
Event horizon · 2GM/c²
Photon sphere · 3GM/c²
ISCO · 6GM/c²
Stable orbit / test mass
Unseel.com · Innermost Stable Circular Orbit: The Edge Beyond Which Orbits Plunge