Physical principle of retrograde Mars.

From an astronomical point of view, the orbits and speeds of the earth and the planets orbiting the sun are different.

Astrology is based on the geocentric theory, so if you look at the earth, you will find that some planets will go retrograde, as shown in the following figure:

The inner ring on the left is in the orbit of the earth, and the outer ring is in the orbit of Mars. They all orbit the sun counterclockwise at the center.

On the right is the position of Mars in the twelve constellations as seen from the earth.

Because the orbit and speed are different, observe the position of Mars in the constellation from the earth.

You will find that Mars sometimes moves in the opposite direction of the twelve constellations.

As shown above:

When the earth moves from ③ to ④ and ⑤, from the earth, Mars is retrograde.

Where B is the "pre-retrograde stagnation period" and C is the "pre-anterograde stagnation period".