Relation between solar sidereal and synodic rotation axes

Kinematic picture concerning the solar synodic and sidereal rotation axes has been considered in some detail. Large changes in the synodic angular rotation velocity and the position of the synodic rotation pole have been found for some hypothetical cases of out-of-ecliptic intra-Mercurian orbits. The influence of solar differential rotation and variable planetary velocity along the orbit have been taken into account and a continuous set of co-existing synodic poles oscillating around a mean position has been found. The relevant numerical values for the Earth are given and the possibility of detecting the existence of the two rotation axes has been pointed out.