1862 H. Spencer ii. x. §83 A slow change in the position of the orbit-plane.
1953 A. F. O'D. Alexander in M. Davidson iv. 203 Pluto's path never crosses Neptune's..for its orbit-plane is inclined 17° to the ecliptic plane.
2002 (Nexis) 17 Jan. Flight controllers..changed the inclination of the orbit, the angle between the orbit plane and the Mars equator, to 93.1 degrees.