From this link http://math.ucr.edu/home/baez/physics/Relativity/GR/grav_speed.html it says that
Putting a "light travel delay" (technically called "retardation") into newtonian gravity would make orbits unstable, leading to predictions that clearly contradict Solar System observations.
Does anyone know how fast would an orbit "destabilize" under retarded Newtonian gravity? How quickly would we observe a deviation between Newtonian orbits and retarded Newtonian orbits if we were to simulate them?
Essentially, I'm looking for any concrete calculations or simulations.