Retrogrades: Apparent Motion, Symbolic Meaning
A planet does not literally reverse its orbit around the Sun. Retrograde motion is an apparent reversal against the background stars caused by changing viewing geometry as Earth and the planet move in their orbits.
Why astrology talks about retrogrades
Astrological traditions treat apparent reversal as symbolically meaningful, often emphasizing review, internalization, delay, reconsideration, or altered expression. Those meanings are interpretive conventions, not astronomical measurements.