In contrast to the geocentric view, what does the heliocentric model explain retrograde motion as?

Answer

An observational artifact of Earth passing a slower outer planet.

The heliocentric view transforms retrograde motion from a true planetary action (requiring epicycles) into an apparent observational artifact resulting from Earth overtaking an outer planet in its own orbit.

In contrast to the geocentric view, what does the heliocentric model explain retrograde motion as?
modelastronomystrengthWeaknessgeocentric