:I suppose the word apparent is appropriate when it is assumed that any observer who is aware he is looking at things from a rotating point of view should keep that in the back of his mind, and should at all times be also imagining the same motion as seen from a non-rotating point of view. 

 :For example, suppose a satellite is brought into a circumpolar orbit, and the orbit is highly eccentric, going several Earth diameters away, and then almost skimming the Earth. As seen from a point of view that is stationary with respect to the Earth that would show up as a rather corkscrew shaped trajectory. 

 :It seems like a good idea then, to keep in the back of one's mind that the natural celestial motion is motion in a plane. That is what celestial bodies orbiting other celestial bodies do. Astronomers find double stars, and those double star system are always seen to move in a plane. To my knowledge, Astronomers never have to transform to make it a plane, the doppler shifts they record are always consistent with two suns in planar orbit around each other.  |