The geocentric astronomers since the time of the Greeks observed that while the Sun appeared to travel through the background stars directly, all planets would occasionally process a loop against the background stars -
https://apod.nasa.gov/apod/ap100613.html
Copernicus determined the direct/retrogrades were an illusion caused by the faster Earth overtaking the slower moving planets
https://apod.nasa.gov/apod/ap011220.html
The faster moving Venus and Mercury and their direct/retrograde motions are entirely different as they process a real and actual loop around the parent Sun hence their loops are not illusory -
http://www.insideastronomy.com/index...-venus-phases/
It would be helpful for those who show up in classrooms or at those star parties to enjoy how we see the faster and slower moving planets from a moving Earth and distinguish what are illusory looping motions from what are the normal circuits of the planets around our parent star.