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by Bob Berman

  In any case, a meteoroid’s speed is less crucial than its direction. What matters is whether it’s barely catching up to Earth from behind or instead hitting us head-on. That’s what’s all-important. The August 11 meteors, those famous Perseids, smash into us head-on. So we witness the violence of their orbital speed added to our own for a combined impact velocity of thirty-eight miles per second. The November Leonid meteors do the same thing. These screaming shooting stars streak across the sky in a mere second or two. No time to say, “Hey, look at that!” Glance down and you miss them.

  But the December 13 Geminid meteors arrive here at a 90-degree angle relative to our orbital direction. There is no head-on collision. They’re like a car backing out of a driveway and crunching softly into ours from the side. The impact speed is just half that of the others. They only streak at twenty miles a second, and it shows as they lope lazily across the heavens. In the vast majority of cases, they are even too slow to create glowing trains behind them, unlike fully one-third of the Perseids and Leonids. What’s wild and satisfying is how easy it is, with no telescope or any other equipment, to witness these disparate cosmic velocities.

  That 1908 Tunguska meteor was moving from the east toward the north. At that early hour of the morning, this corresponded to a sideways entry into our atmosphere. Similarly, the Siberian bolide (exploding meteor) of 2013 came in at about eleven miles a second from the sunward direction, sideways to us. Had either come from an overhead direction it would have had far more speed and thus released far more energy. Our thin, dirt-covered 1908 witness, Semen Semenov, whose wife led him back into his house, the windows of which were now broken, may not have fared as well if that had been the case.

  Obviously, celestial movement isn’t necessarily a textbook sort of thing. It parades overhead right in our faces when we take a few minutes to look.

  But if celestial speeds do seem too cerebral, we can bring the whole thing home, quite literally. Remember that our planet is not an isolated island. Comets and asteroids continue to pay us close encounters of the clobbering kind.

  The public has many misconceptions about meteorites—the name for meteors that land. People imagine they’re hot when in truth they’re barely warm, after being flash-frozen by passage through our cold atmosphere. On August 31, 1991, two boys standing on a front lawn in Noblesville, Indiana, saw a meteorite thud into the grass a few feet away and picked it up immediately without harm.

  People also imagine they’re deadly, when the only person ever directly hit, Ann Hodges of Sylacauga, Alabama, was merely bruised when one tore through her roof, struck a console radio, then bounced onto her hip on November 30, 1954.

  To merely state that Ann Hodges was the only person in history to be hit and injured by a meteorite is to simplify an amazing story. It started that afternoon when Ann, not feeling well, fell asleep on her living room sofa—in a rented white house located across the street from the Comet Drive-In Theatre, whose neon logo depicted a zooming, meteorlike object.

  Hodges was awakened by the eight-pound metallic object crashing at high speed through the living room ceiling. Before she could react, it bounced off the radio, struck her left hip, and bruised her left hand. The incident quickly drew crowds of TV and print reporters and put the thirty-four-year-old woman in the history books. A footnote was added for area physician Moody Jacobs, the only doctor ever to treat someone struck by an object from outer space.

  But Ann Hodges did not gain any benefit from this historic occurrence—unlike, say, eighteen-year-old Michelle Knapp of Peekskill, New York, whose life was changed by a 1992 meteorite encounter with her car. For Ann, the trouble began when her husband, Eugene Hulitt Hodges, and she were upset at the crowds descending on their home, then amazed and angered that police officers and government officials took away the meteorite without the family’s permission.

  The Hodgeses worked with a lawyer to eventually secure the meteorite’s return, but their hopes of making a fortune from the stone quickly faded when their landlady, Birdie Guy, claimed the meteorite was rightfully hers and fought for its custody in court. Legal battles over its ownership and multiple costly appeals all went against the Hodgeses, while public sentiment went against the “greedy” landlady, as she was generally depicted in news reports. The Hodgeses finally settled, and Guy accepted five hundred dollars in lieu of the meteorite, but by then the headlines were long over and the meteorite was no longer a hot or valuable item. The couple eventually turned it over, for small compensation, to the Alabama Museum of Natural History at the University of Alabama in Tuscaloosa, where it remains on display.

  The only person with a positive experience in the entire celestial encounter was a farmer named Julius Kempis McKinney. On December 1, 1954, the day after the meteorite struck the Hodges house, McKinney was driving a mule-drawn, firewood-laden wagon a few miles away when the animals balked at a black rock in the road. McKinney kicked the odd black stone off the road and continued home. But later, upon hearing news reports of the Hodges incident, McKinney returned to the site. He took the rock home and let his children play with it.

  He trusted only his postman with the information. The postman helped McKinney find a lawyer, who negotiated an amazing price for the meteorite’s sale. The purchaser was an attorney from Indianapolis acting on behalf of the Smithsonian Institution.

  Mineralogy experts confirmed that the three-pound rock was indeed a fragment of the larger Hodges meteorite; it is actually common for a meteoroid to shatter or explode into multiple pieces in the air before hitting the ground. Although the sale price was never revealed, it was enough for the McKinney family to purchase a car and a new house. This unexpected good fortune was a rare event for an African American in that state in that period of history, when racial inequality was the norm.

  Is all this sufficient for a movie plot? Bill Field, who as a five-year-old in Sylacauga saw the meteor streak across the sky, leaving a white trail, and heard a loud sonic boom—a somewhat quieter version of what Siberian townspeople experienced in 2013—grew up to be a filmmaker. He researched the incident and what happened to all the people involved and successfully sold his movie script to 20th Century Fox. But no film was ever made.

  As for Ann Hodges, she later said she’d been permanently changed—not by the six-inch bruise on her left hip but by the emotional scars resulting from the legal fights and disappointments. She died of kidney failure at a Sylacauga nursing home in 1972, at the age of fifty-two.

  History also records a Franciscan friar who was reportedly killed in Milan in the seventeenth century by a two-inch meteor that severed an artery in his leg. But who can say for sure? For all anyone knows, it could have been a stray musket shot. Confirmation is lacking. And in 2009, a German boy claimed that his finger had been injured by a pea-size meteorite that appeared “after a flash of light” and then “buried itself in the road.” Despite global headlines, however, this story is not credible at all. Ann Hodges’s bruise remains the only authenticated human injury from a hurtling space object.

  Meteors provide the only visible physical interchange between Earth and the heavens. It’s the sole visual link between what’s “up there” and our terrestrial lives. A meteor’s fall to earth is sudden, and just to add a little spice, there’s even that hint of danger.

  Hint or not, Armageddon lovers never tire of the “peril from space” motif—the fear of a giant Earth-smiting stone from hell, a Tunguska meteor on steroids. New end-of-days predictions sprout like poppies, only to dissipate when the dreaded date passes harmlessly and is as promptly forgotten as an opium dream. To appreciate the peril realistically, you have to know how it works.

  Instead of watching meteors in space—few of which survive their trip through the atmosphere but instead disintegrate quietly into dust—we should contemplate the rare dramatic meteors that have made it all the way to the ground. We won’t even talk about the really bad events that altered history, including the dinosaur-ending K-T impact sixty-five mi
llion years ago, which crashed into the raptors’ favorite Yucatán beach at Chicxulub. Or the even worse Permian “great dying” 251 million years ago, which destroyed most of the planet’s genera as though they were doodles on a chalkboard and nearly erased the intricate, interconnected biosphere. Such events typically involve asteroids more than a mile wide, the kind that seem to hit us every few hundred million years or so. Much more common are the smaller stones in the three-to twenty-five-pound category, which damage homes almost yearly, usually after an expensive renovation.

  Meteoroids that make it to the ground are not the meteor-shower variety, which are usually composed of flimsy ices. The survivors are, instead, hardy stony or metallic pieces of asteroids or even fragments of the moon or Mars. They arrive without warning.

  A meteoroid can weigh a ton as it strikes our atmosphere; that was the estimated mass of the intruder that broke into dozens of fragments over a Chicago suburb on March 26, 2003. One small piece penetrated a teenager’s bedroom, hit his printer, and shattered a full-length mirror. Bad luck? It could have been much worse.

  A meteoroid traveling through space encounters Earth at a sizzling seven to forty-four miles per second. If it weighs more than one hundred thousand tons our atmosphere won’t slow it down in the slightest: it slams into the ground at full cosmic velocity.

  At the other extreme, if the meteoroid is less than eight tons, friction from the air robs it of all its original speed. Then its impact, like that of falling garbage or flying squirrels, is strictly determined by terminal velocity. Happily, these lower-mass objects are the rule.

  At a height of about ten miles, or fifty thousand feet, a meteorite slows to two or three miles per second and no longer glows. From that altitude on down it’s an invisibly dark tumbling piece of rock, which can be mostly stone or a half-iron, half-nickel amalgam. Nonetheless its seven-thousand-mile-an-hour velocity, three to six times faster than a bullet, gives a one-pound meteor enough kinetic energy to bring down a jetliner. It hasn’t yet happened, but it could.

  Continuing downward, unobservable, the meteoroid’s encounter with increasingly thick air slows it to a terminal velocity of around 250 miles per hour. This is its final speed as it strikes the ground. Or anything else.

  Buildings are penetrated every year or so in North America alone. Animals, standing naked outdoors, have also fared poorly:

  May 1, 1860: A horse is killed by a meteorite in Concord, Ohio.

  March 11, 1897: A rain of many stones in West Virginia kills another horse.

  June 28, 1911: A meteor later found to have come from Mars kills a dog on the outskirts of Alexandria, Egypt.

  October 15, 1972: A cow is killed by a meteorite in Valera, Venezuela.

  Cars seem to attract meteors, too. One was quietly parked in its garage on September 28, 1930, in Benld, Illinois, when a meteor penetrated the garage roof, the car’s roof, and the car’s wooden floorboards before bouncing up off the muffler and coming to rest in the seat material, inaugurating a long love affair between asteroid fragments and automobiles.

  In the past quarter century the most spectacular encounter was the parked Chevy in Peekskill, New York, whose trunk was destroyed by a twenty-six-pounder on October 9, 1992. Its eighteen-year-old owner found her life changed by the sixty-nine thousand dollars paid to her by a collector. (He wanted the crumpled car as well as the meteorite, and she said, “Sure.” A beat-up, ten-year-old Malibu whose insurance didn’t even cover the damage? Are you kidding? Take it!)

  Just between 2002 and 2010, meteorites entered at least seven homes, including two in the United States. The freshly landed stones are usually “barely warm” and have a black fusion crust.

  There is no terminal velocity on airless bodies such as Mercury and the moon, where meteoroids captured by gravity keep gaining speed up to a maximum that equals that planet’s escape velocity. On Earth it’s twenty-five thousand miles per hour. If there were no air, meteorites wouldn’t just penetrate roofs and floors. They’d keep going until they converted the basement playroom and much of the surrounding neighborhood into a huge crater. After all, kinetic energy equals the meteorite’s mass times the square of its speed. A meteor reaching your kitchen table at 250 miles an hour is 1002, or ten thousand, times less damaging than if it had struck at even a low space speed of twenty-five thousand miles per hour.

  That’s why meteor stories have, to date, tended to be whimsical (or, in the case of the 2013 Siberian event, scary and laceration-producing) rather than tragic.

  Meteor landings, such as the dozens that occurred in a Ugandan village in 1992, are sometimes preceded by widely observed celestial fireworks. My favorite meteor story involved just such a scenario in the northeastern United States on November 30, 1981.

  An alarmed woman phoned our observatory (the Overlook Observatory, which I have owned and operated since 1982) that night to report a fiery ball slashing across the heavens, lighting up the countryside. Some people assume that observatories are UFO-reporting stations, and we get regular inquiries concerning lights in the sky. But like most celestial phenomena, this had an easy explanation, and I told the woman that the sparking object was probably just a meteor: nothing unusual. I couldn’t know, however, that things were anything but routine a mere hundred miles to our east.

  Observers in central Connecticut were noticing the same brilliant light in the sky, but to them it was motionless. There’s only one way it could appear stationary: it was coming straight toward them!

  The grapefruit-size meteor not only survived its passage through the atmosphere, it crashed through the roof of a house in Wethersfield, Connecticut, where Robert and Wanda Donohue were watching the TV show M*A*S*H* in the next room. They later told me that it was the loudest sound they’d ever heard. Rushing into a room that was now filled with dust, where furniture had been overturned, they found a hole in the ceiling.

  Connecticut has no Meteor Police, and after the Donohues called 911 some firemen came to their house along with the town’s uniformed officers. It was a fireman who found the six-pound meteor under the dining room table, where it had settled after a couple of high-speed bounces that left behind scuff marks on the carpet and ceiling.

  They almost weren’t surprised. Eleven years earlier, in April of 1971, the last time a meteorite had hit a house anywhere in the United States, the impact point was Wethersfield, Connecticut. The same town. In one of the strangest coincidences of our time, a house barely more than a mile from the Donohues’ had been struck.

  The only plausible explanation for the same town being hit consecutively is that Wethersfield is a suburb of Hartford, the headquarters for many insurance companies. This is where statisticians and actuaries live. They’re the ones who know how impossible this is.

  (In case you’re curious, the answer is yes: the Donohues’ insurance completely covered them for the meteorite damage. They deserved it. A couple of years later, Bob and Wanda generously donated the cosmic house wrecker to a museum in New Haven.)

  With all these ongoing impacts, should we worry, really? Maybe a little. That famous Tunguska event occurred over a part of Asia at a time when the world’s population was just a third of what it is today. If it happened now, over a city, we could have twenty million fatalities.

  Significant meteoroids keep coming in, like the six-foot-wide exploding air burster that rattled windows in Nevada on April 22, 2012, and of course the 2013 Siberian spectacle. Gemologists and adventurers quickly converged on both places like Black Friday shoppers and started finding meteorites—most of which bored precise holes into the snow—in Northern California the next week and in and around the Russian town of Chelyabinsk the very next day. But experts now estimate that a truly damaging meteorite impact hits our world only every few hundred years. Then and now, the most likely ground zero is somewhere over the ocean.

  The asteroid Apophis will come extremely close to us on April 13, 2029, at a speed of nineteen miles a second. It will barely miss us then, passing betwe
en the ground and our television satellites 22,300 miles up! If its orbit is altered in a precise but unlikely way by that near miss, it could hit us the next time it comes by, on April 13, 2036, with an impact explosion equivalent of five hundred hydrogen bombs. However, the chance of that collision with Earth is currently pegged by NASA experts at only one in a quarter million, which matches the odds of your teenager grabbing the vacuum and spontaneously cleaning the entire house.

  Far beyond our solar system, truly off-the-charts velocities—like those of galaxies slamming into each other at a few percent of the speed of light—will never affect us. The cosmos is crammed with rapid motion for the mind’s musings only, an insurance headache for alien civilizations alone.

  The fastest you and I—and everything else on our forgiving planet—travel through space? Aristarchus nailed the twin spin-plus-orbit motions 2,300 years ago. Combined with Eratosthenes’s spot-on determination of our planet’s size a century later, the small minority of humans who eschewed geocentrism knew before Christ was born that Earth spins.

  When the four eighteenth-and nineteenth-century transits of Venus across the solar disk let astronomers pin down the sun’s true distance from us, we could then finally calculate our exact orbital speed: 66,600 miles per hour, or 18.5 miles per second. We’ll never feel it, because everything around us is moving, too, plus there’s no palpable acceleration or motion change.

  Only one other major earthly speed needed to be added. The all-time biggie. This was uncovered by Harlow Shapley a century ago. As we circle the sun, that star itself whooshes around the galaxy’s own center, taking us along for the ride. Our world thus partakes of our galaxy’s spin at a whopping 140 miles a second. That’s the very fastest terrestrial speed that makes any sense, because beyond the galaxy there’s no fixed reference point. We say the Andromeda galaxy is approaching us at seventy miles a second. But we could just as easily regard it as motionless and say that we are moving toward it at that speed. Or we could split the difference and say each travels at thirty-five miles per second. All we know is that the gap between us is shrinking. Because we lack any stationary reference grid for extragalactic motion, our ability to include calculations of speed in our movement story stops at the property lines of the Milky Way. Beyond that, spaces between galaxy clusters increase, but no one can pin down who, exactly, is moving.