Mercury Retrograde (Mercury Rx) makes the orbit of Mercury look as if it is moving backwards once the planet’s orbit has reached maximum distance and has to orbit in front of the Sun. This left-to-right motion as the planet transits across the sun, as it appears to look like it is going in reverse is called retrograde motion.
This video will illustrate what the retrograde motion is in the sky. This is a time lapse on the same time at noon. Then we turn the lights off so that you can see the other planets more clearly.