By Fire Well and Tree

Photo by ZCH: https://www.pexels.com/photo/planet-mercury-in-full-shot-photography-12498795/ I know, people say that a lot...so... Okay firstly, retrograde is a real thing, astronomically.  You can find a more technical, but still accessible, explanation  here .  If you think about cars going around in several lanes of traffic, going the same speed and starting out parallel, eventually the the car in the shortest lane (usually the inside track) will get ahead of the car in the longer lane. It can  appear  then that as the first car passes the second, the second is actually going backwards.  If we think about planets in our solar system, they are all doing the same thing, and sometimes they pass each other. When Earth "passes" a planet during its orbit, that other planet is said to be retrograde.  Looking at them in the sky, the planet appears to move backward.    How often a planet becomes retrograde relative to Earth depends on not only its proximity to the Earth, but also