Resonances occur when period of the perturbing force is commensurable with the perturbed body’s
orbital motion (2/1 resonance corresponds to a perturbing force whose one cycle is completed in two orbits
of the perturbed body; two cycles are completed during one orbit in the case of 1/2 resonance, etc.). They
constitute a rather special (and difficult) category of time-dependent perturbations, as we demonstrate
using several examples of an asteroid perturbed by Jupiter’s gravitational pull.
We start with the 1/1 resonance, which has some unique features, not shared by other resonances.
