Planetary orbits. Stability is important there. But 3 and greater body problem in Newtonian mechanics is inherently chaotic. Add in spin-orbit coupling, rela

Planetary orbits. Stability is important there. But 3 and greater body problem in Newtonian mechanics is inherently chaotic. Add in spin-orbit coupling, relativity and other effects, and its a real mess, with no exact closed form solutions. That said, we can predict, with some level of accuracy the stability of of orbits in a number of cases. Approximate solutions can be managed with various levels of theory, perturbations, and numerical simulation.