In the heliocentric system, how is apparent retrograde motion explained? planets nearer to the sun orbit faster than planets further from the sun. when an inner planet 'overtakes' an outer planet, the outer planet appears to move backward each planet's orbit is in the shape of an ellipse. othe earth occasionally travels slower in its orbit and when this happens, the other planets appear to move backward. oeach planet is on a rotating epicycle, which in turn orbits the sun. return to site