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Mercury passing the Sun.

What is Mercury in Retrograde, and Why Do We Blame Things On It?

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Mercury passing the Sun.

Crashed computers, missed flights, tensions in your workplace—a person who subscribes to astrology would tell you to expect all this chaos and more when Mercury starts retrograding for the third time this year on Sunday, August 13 (or August 12, depending on where you live). But according to an astronomer, this common celestial phenomenon is no reason to stay cooped up at home for weeks at a time.

"We don't know of any physical mechanism that would cause things like power outages or personality changes in people," Dr. Mark Hammergren, an astronomer at Chicago's Adler Planetarium, tells Mental Floss. So if Mercury doesn’t throw business dealings and relationships out of whack when it appears to change direction in the sky, why are so many people convinced that it does?

THE HISTORY

Mercury retrograde—as it's technically called—was being written about in astrology circles as far back as the mid-18th century. The event was noted in British agricultural almanacs of the time, which farmers would read to sync their planting schedules to the patterns of the stars. During the spiritualism craze of the Victorian era, interest in astrology boomed, with many believing that the stars affected the Earth in a variety of (often inconvenient) ways. Late 19th-century publications like The Astrologer’s Magazine and The Science of the Stars connected Mercury retrograde with heavy rainfall. Characterizations of the happening as an "ill omen" also appeared in a handful of articles during that period, but its association with outright disaster wasn’t as prevalent then as it is today.

While other spiritualist hobbies like séances and crystal gazing gradually faded, astrology grew even more popular. By the 1970s, horoscopes were a newspaper mainstay and Mercury retrograde was a recurring player. Because the Roman god Mercury was said to govern travel, commerce, financial wealth, and communication, in astrological circles, Mercury the planet became linked to those matters as well.

"Don’t start anything when Mercury is retrograde," an April 1979 issue of The Baltimore Sun instructed its readers. "A large communications organization notes that magnetic storms, disrupting messages, are prolonged when Mercury appears to be going backwards. Mercury, of course, is the planet associated with communication." The power attributed to the event has become so overblown that today it's blamed for everything from digestive problems to broken washing machines.

WHAT IS IT ACTUALLY?

Though hysteria around Mercury retrograde is stronger than ever, there's still zero evidence that it's something we should worry about. Even the flimsiest explanations, like the idea that the gravitational pull from Mercury influences the water in our bodies in the same way that the moon controls the tides, are easily deflated by science. "A car 20 feet away from you will exert a stronger pull of gravity than the planet Mercury does," Dr. Hammergren says.

To understand how little Mercury retrograde impacts life on Earth, it helps to learn the physical process behind the phenomenon. When the planet nearest to the Sun is retrograde, it appears to move "backwards" (east to west rather than west to east) across the sky. This apparent reversal in Mercury's orbit is actually just an illusion to the people viewing it from Earth. Picture Mercury and Earth circling the Sun like cars on a racetrack. A year on Mercury is shorter than a year on Earth (88 Earth days compared to 365), which means Mercury experiences four years in the time it takes us to finish one solar loop.

When the planets are next to one another on the same side of the Sun, Mercury looks like it's moving east to those of us on Earth. But when Mercury overtakes Earth and continues its orbit, its straight trajectory seems to change course. According to Dr. Hammergren, it's just a trick of perspective. "Same thing if you were passing a car on a highway, maybe going a little bit faster than they are," he says. "They're not really going backwards, they just appear to be going backwards relative to your motion."

Embedded from GIFY

Earth's orbit isn't identical to that of any other planet in the solar system, which means that all the planets appear to move backwards at varying points in time. Planets farther from the Sun than Earth have even more noticeable retrograde patterns because they're visible at night. But thanks to astrology, it's Mercury's retrograde motion that incites dread every few months.

Dr. Hammergren blames the superstition attached to Mercury, and astrology as a whole, on confirmation bias: "[Believers] will say, 'Aha! See, there's a shake-up in my workplace because Mercury's retrograde.'" He urges people to review the past year and see if the periods of their lives when Mercury was retrograde were especially catastrophic. They'll likely find that misinterpreted messages and technical problems are fairly common throughout the year. But as Dr. Hammergren says, when things go wrong and Mercury isn't retrograde, "we don't get that hashtag. It's called Monday."

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Mercury passing the Sun.
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Big Questions
What is Duck Sauce?
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A plate of Chinese takeout with egg rolls and duck sauce
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We know that our favorite Chinese takeout is not really authentically Chinese, but more of an Americanized series of menu options very loosely derived from overseas inspiration. (Chinese citizens probably wouldn’t recognize chop suey or orange-glazed chicken, and fortune cookies are of Japanese origin.) It would also be unusual for "real" Chinese meals to be accompanied by a generous amount of sauce packets.

Here in the U.S., these condiments are a staple of Chinese takeout. But one in particular—“duck sauce”—doesn’t really offer a lot of information about itself. What exactly is it that we’re pouring over our egg rolls?

Smithsonian.com conducted a sauce-related investigation and made an interesting discovery, particularly if you’re not prone to sampling Chinese takeout when traveling cross-country. On the East Coast, duck sauce is similar to sweet-and-sour sauce, only fruitier; in New England, it’s brown, chunky, and served on tables; and on the West Coast, it’s almost unheard of.

While the name can describe different sauces, associating it with duck probably stems from the fact that the popular Chinese dish Peking duck is typically served with a soybean-based sauce. When dishes began to be imported to the States, the Americanization of the food involved creating a sweeter alternative using apricots that was dubbed duck sauce. (In New England, using applesauce and molasses was more common.)

But why isn’t it easily found on the West Coast? Many sauce companies are based in New York and were in operation after Chinese food had already gained a foothold in California. Attempts to expand didn’t go well, and so Chinese food aficionados will experience slightly different tastes depending on their geography. But regardless of where they are, or whether they're using the condiment as a dipping sauce for their egg rolls or a dressing for their duck, diners can rest assured that no ducks were harmed in the making of their duck sauce.

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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Mercury passing the Sun.
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Big Questions
Can You Really Go Blind Staring at a Solar Eclipse?
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A total solar eclipse will cut a path of totality across the United States on August 21, and eclipse mania is gripping the country. Should the wide-eyed and unprotected hazard a peek at this rare phenomenon?

NASA doesn't advise it. The truth is, a quick glance at a solar eclipse won't leave you blind. But you're not doing your peepers any favors. As NASA explains, even when 99 percent of the sun's surface is covered, the 1 percent that sneaks out around the edges is enough to damage the rod and cone cells in your retinas. As this light and radiation flood into the eye, the retina becomes trapped in a sort of solar cooker that scorches its tissue. And because your retinas don't have any pain receptors, your eyes have no way of warning you to stop.

The good news for astronomy enthusiasts is that there are ways to safely view a solar eclipse. A pair of NASA-approved eclipse glasses will block the retina-frying rays, but sunglasses or any other kind of smoked lenses cannot. (The editors at MrEclipse.com, an eclipse watchers' fan site, put shades in the "eye suicide" category.) NASA also suggests watching the eclipse indirectly through a pinhole projector, or through binoculars or a telescope fitted with special solar filters.

While it's safe to take a quick, unfiltered peek at the sun in the brief totality of a total solar eclipse, doing so during the partial phases—when the Moon is not completely covering the Sun—is much riskier.

WOULDN'T IT BE EASIER TO JUST TELL YOUR KIDS THEY WILL GO BLIND?

NASA's website tackled this question. Their short answer: that could ruin their lives.

"A student who heeds warnings from teachers and other authorities not to view the eclipse because of the danger to vision, and learns later that other students did see it safely, may feel cheated out of the experience. Having now learned that the authority figure was wrong on one occasion, how is this student going to react when other health-related advice about drugs, alcohol, AIDS, or smoking is given[?]"

This story was originally published in 2012.

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