As you saw in part a, io's elliptical orbit is necessary to its tidal heating. this elliptical orbit, in turn, is a result of the orbital resonance among io, europa, and ganymede. this orbital resonance causes io to have a more elliptical orbit than it would otherwise, because and ganymede are unusually large moonseuropa and ganymede always pull on io from the same direction as jupiter pulls on ioio periodically passes europa and ganymede in the same orbital positionall three moons orbit with the same period, staying aligned at all times