Direct/retrograde loops

The geocentric astronomers up to the time of Copernicus saw that all planets would occasionally process a loop against the background stars -

https://apod.nasa.gov/apod/ap031216.html

Copernicus explained that this loop was illusory and due to the orbital motion of the Earth overtaking the slower moving planets as Jupiter and Saturn are seen to do as they fall behind in view -

https://apod.nasa.gov/apod/image/011...2000_tezel.gif

Unlike the illusory loops of the slower moving planets, the faster moving Venus and Mercury show actual loops around the Sun -

http://www.insideastronomy.com/uploa...0_7_128459.jpg

Their direct/retrogrades are simply a reflection of their smaller orbital circumference (compared to the Earth) and their faster orbital motion as they swing in front of the Sun and then move in the opposite direction behind the Sun.