On the tidal force from the body circulating on an elliptic orbit

The problem of the tidal effects on the central spherical planet from the disturbing body (satellite), moving in an elliptical orbit is studied. We performed the averaging of the tidal potential over the period of the satellite and proved that regardless of the value of the orbit eccentricity the perturbation force of the body was, upon the average, purely radial, as if the orbit of the satellite had been just circular.