Every so often, an aspect of woo finds its way into the mainstream, being taken up and mentioned by people who generally don’t keep up with or believe in the body of thinking it comes from. From my very biased sample of facebook friends, it seems that Mercury retrograde is one of them. People who never otherwise mention astrology will write “Thank goodness Mercury is coming out of retrograde, it’s been a rough week” or “Missed two buses and an essential phone call: damn you, Mercury retrograde!” And since I only rarely lecture to people on their own facebook walls, I thought I’d get out all my frustrated pedantry here.
First, a brief explanation of what “Mercury in retrograde” even means. All celestial bodies, as observed from Earth, move from east to west in a daily arc across the sky: this apparent motion is caused by the Earth’s daily rotation on its axis. The stars all stay in the same relative position to one another, but the planets move from night to night, so that one day they’ll appear near one constellation, and the next day they’ll have moved slightly further away from it. Normally this relative motion is also eastward, but occasionally a planet goes into a phase where it’s moving westward relative to the stars. This is called retrograde motion, and yes, all of the planets do it — Mercury just does it more often. It’s caused by the relative positions of Earth and the planet in question, as they both move through their orbit.
So there’s nothing mystical about it, just a natural effect of perspective when you have two moving objects moving at different rates.
For astrologers (and mythology buffs) Mercury governs transportation and communication, and when Mercury is in retrograde you can expect to have difficulties in both of these areas. And now we begin to see why the “Mercury retrograde” meme has caught on, even among people who never notice or care when Mars or Venus is in retrograde. Transportation and communication, in our modern world, tend to be based on complex systems that are easy to mess up. And they also tend to form the bedrock of our lives: some day write down how much time per day you aren’t engaged in either transportation or communication of some sort. So breakdowns in transportation or communication tend to be frustrating and cause further problems, and they happen often. And when a human brain faces a frustrating, obstructive issue, it wants to try to make sense of it. So if you’re a fairly ordinary person who’s heard of the whole Mercury retrograde thing from your astrology-believing friends, and one day you miss your train and later you’re stuck on hold for two hours, and still later you have trouble with a project because you and your colleague interpreted the requirements differently… well then your frustrated brain is looking for answers to “Why is everything so difficult today?” And then you think to check if Mercury is in retrograde, and if it is, all sorts of little reward fireworks go off in your brain. There’s an explanation! These issues might be out of your control, but at least they are predictable and explicable, and that feels so much better, cognitively, than just having a rough day for no particular reason.
And if, perchance, Mercury isn’t in retrograde on this particular day, you probably barely notice, since you weren’t all that invested in the myth to begin with, and you go on to look for other reasons why today sucks. And if this happens multiple times over the course of a year, and you get two or three “Yes! My day sucks because of Mercury!” moments and twelve or thirteen “Nah, it must be something else” moments, you will probably start to believe a little in Mercury retrograde. Your brain is a bad statistician; it remembers things that have emotional impact, and the “Yes! Explanation found!” emotional impact is much more powerful than the “Nah, must be something else.”
And if you already believe in Mercury retrograde, you’ll start getting confirmations pretty quickly. Apart from illness, nearly everything that goes wrong for a person in an industrialized society can be, by some stretch of the imagination, connected to either communication or transportation. Check out this piece from Astrology Zone on what Mercury retrograde means for you: aside from the obvious travel, mail, and email issues, it predicts that Mercury retrograde might cause your DVD player to break or your boyfriend to fight with you. Also, just in case all the bases aren’t covered, Mercury retrograde can cause some things that were broken to fix themselves, so if you have an unexpected success in the area of transportation and communication (as broadly interpreted as possible), that counts too! If you know when Mercury is in retrograde, it would be incredibly improbable for you not to receive dozens of confirmations that it’s having an effect during that time.
What tickles me about the Mercury retrograde phenomenon is that it always reminds me of another colossal case of human bias. The apparent retrograde motion of the planets confused the hell out of ancient astronomers. The going theory for hundreds of years was that the stars were part of a rotating sphere, moving cleanly around the earth which sat at the center of the sphere. The sun, moon, and planets were thought to move on inner spheres, concentric with one another and moving at different rates. Most philosophy at the time accepted a few basic principles (drawing heavily from Aristotle): that the celestial bodies were perfect and unchanging, while the earth was subject to change and decay; that a circle was the perfect form of motion, and thus all celestial motions must be circular. The system of concentric celestial spheres worked great with this philosophy, except that the planets sometimes didn’t. What was going on with that retrograde motion? Astronomers, most notably Ptolemy, worked out huge elaborate systems to explain the irregular planetary motion in terms of the circles that Aristotelian physics demanded. When something fits most of our observations, as well as our underlying philosophy, we will often go to absurd lengths to make the few remaining inexplicable bits fit before we’ll stop and consider that maybe the entire system is wrong.