You have probably heard several versions of this phrase before, usually accompanied by a sigh. Someone is having a bad day. Or he’s in a bad mood. Or nothing seems to go right despite his best efforts. And so he blames Mercury, the smallest planet in our solar system and closest to the Sun. Everything is Mercury’s fault. The damn planet is retrograde! Among other things, it is happening in these days.
The idea that planets can influence people’s lives is a fundamental principle of astrology, the divinatory practice of drawing meaning from the cosmos that has existed in various declinations for millennia. The belief that Mercury, in particular, can have problematic effects is a fairly recent development, dating back to the 1980s, according to an in-depth article in Harper’s Bazaar. The modern form of this belief (complete with inevitable memes) has emerged in the last century. The story even concerns Taylor Swift and her complaint about the alleged astrological chaos brought by Mercury, contained in a 2014 MTV video.
Astrology is not a science. However, the phrase “Mercury is retrograde” describes a real phenomenon, perfectly explained by people who like astrologers think a lot about Mercury, but unlike astrologers would never dream of blaming the planet when they forget the keys at home: planetologists.
An optical illusion
Mercury in the retrograde phase does not mean that there is something strange in the orbit of the planet. The phenomenon concerns the way the planet appears to us in the sky, as a small white dot in the hours immediately after sunset and immediately before dawn, explains David Rothery, planetologist at the Open University in England. Most of the time Mercury moves from west to east relative to the stars in the night sky, but several times a year the progression changes, and the motion appears from east to west.
The reason for this inversion is related to the relative positions of Mercury and the Earth around the Sun. Mercury orbits closer to the Sun than the Earth, so the small planet travels much faster around the star, completing a complete orbit in just 88 days , against 365 of the Earth. Due to this different trajectory it happens that Mercury “doubles” the Earth during our planet’s revolutionary journey around the Sun, “overtaking us on the inside lane,” explains Rothery. When this happens, that little white dot in our sky seems to reverse course and move, little by little every night, in the opposite direction. Eventually the Earth recovers and Mercury seems to change direction again. This phenomenon occurs three or four times a year and lasts about three weeks.
Therefore, even if the phrase “Mercury in retrograde phase” has a concrete basis, it is only an optical illusion. Everything happens exclusively from our point of view on Earth. This visual effect also occurs on the surface of Mercury, but with a different celestial object. “Sometimes the Sun moves in the opposite direction when viewed from the surface of Mercury,” says Nancy Chabot, a planetary scientist at Johns Hopkins University’s applied physics laboratory.
Neglected planet
When Mercury appears to change course from our perspective, the planet is actually proceeding on its way following its usual path around the Sun. lost email or commuter travel delays that astrologers talk about. Mercury, of course, has no influence on the daily life of human beings, just like any other planet. This is why I feel the irrational urge to defend Mercury, which is simply in the wrong place at the wrong time.
By the way Mercury is already one of the most neglected planets in our solar system. Mars receives all rovers. Jupiter is the subject of countless spectacular photographs. Venus is brought up in the debate on the existence of aliens. Even Uranus has recently become the center of attention. Mercury has no moons or rings. At least Pluto has rings! And Mercury? It gets complaints from people who, as Jo Livingstone wrote in Harper’s Bazar, “know Mercury more as an astrological entity than as a physical planet”. To paraphrase Taylor Swift, I think Mercury would very much like to be left out of this narrative.
“As far as I’m concerned, the only effect this has on events on Earth is that most of the time, when Mercury is retrograde, it is so close to the Sun in the sky that radio communications with the probe located near the planet are affected by interference with the signal, ”explains Rothery. “I’ve never noticed astrological agitation,” she adds. Those who care about it should observe Mercury for themselves in the night sky or look for photos of the planet taken by space missions, to find out “how fascinating is his world“. Mercury has more craters than any other planet in the solar system. And it’s contracting. Slowly, over billions of years, its crust cracks and compresses.
Mercury’s retrograde phase can affect Chabot’s mood, but not for the reasons advanced by astrologers. When the planetologist notices a title on the astrological threat represented by Mercury, check if the published photo was taken by Messenger, a NASA probe that orbited the planet from 2011 to 2015 (the name of the mission is an acronym for Mercury surface, space environment, geochemistry and ranging, Mercury surface, space environment, geochemistry and ray. NASA loves acronyms). “The fact that Mercury is retrograde several times a year means that I can often admire the images from Messenger, and that makes me happy,” explains Chabot, who collaborated on the mission. At the same time, the planetologist is disappointed when astrology articles use images from the Mariner 10 probe. That mission, dating back to the 1970s, immortalized less than half of the planet’s surface. Only with Messenger the human race was able to admire the planet in its entirety, every crater and every crack on its surface burned by the Sun, with hardened ash that shows that in the past the planet was rich in volcanoes.
The Messenger mission ended when the spacecraft ran out of propellant to stay in orbit and crashed on the surface of Mercury. The latest mission dedicated to Mercury, led by the European Space Agency and Jaxa, the Japanese space agency, left Earth in 2018. The spacecraft is still on its way, relying on a series of grazing passes beyond Mercury and Venus to veer towards its goal. The BepiColombo mission, named in honor of the twentieth-century Italian mathematician who made the calculations for the close flyovers, will enter Mercury’s orbit at the end of 2025.
At the end of next week Mercury will reverse direction in the optical illusion in our sky, interrupting the retrograde phase. At the end of June BepiColombo will make its last close flyby, passing just 124 miles (200 kilometers) from the planet’s surface. In that moment he will take sensational images of that rough and so blamed world. He will find no proof of why our days seem to go wrong. The answer to that question, in fact, is much closer to our home.
(Translation by Andrea Sparacino)