Final answer:
Resonance refers to the orbital condition where two objects have periods of revolution in a simple ratio due to gravitational influences. This concept is rooted in Kepler's third law, which relates the orbital period to the semi-major axis of an orbit.
Step-by-step explanation:
When two objects in orbit have periods of revolution that are simple ratios of each other, such as 1 to 2 or 1 to 3, we refer to this orbital condition as resonance. Resonance occurs due to periodic gravitational perturbations one object experiences because of another. A well-known example of resonance is seen with some of the moons of Jupiter, where the gravitational influences between them result in their orbital periods being locked in a ratio.
Resonance is not to be confused with an occultation (which is when one object passes in front of another from the observer's perspective), a conjunction (where two celestial bodies appear near each other in the sky), or a tidal stability limit (related to the point where a satellite can maintain a stable orbit without being pulled apart by tidal forces).
According to Kepler's third law, the square of an object's orbital period is directly proportional to the cube of the semi-major axis of its orbit. This law applies to the orbits of planets and satellites and forms the basis for understanding the dynamics of resonance.