Tilt of Iapetus’ local Laplace plane to Saturn’s equator as a function of Iapetus’ semi-major axis. Here includes the secular effect of Titan. Equation (12) was used to produce this graph and it gives a Laplace plane inclination of around 16° for the semi-major axis of Iapetus today (0.02381 AU). These numbers are represented by the blue lines. This plot also shows that a satellite would usually orbit close to the planet’s equator if its orbit is close to it and would see its orbital plane getting close to the ecliptic as its semi-major axis gets higher. Iapetus lies in-between those two cases.