Death from the Skies! Read Free Page B

vaporized. The air blast created a shock wave that knocked down those trees. The trees at the center were still standing because the blast wave slammed straight down into them; it takes sideways force to knock trees down. Nuclear airburst blasts during weapons tests of the 1950s and 1960s replicated the same pattern.
    While the remote location of the explosion made it hard to study, it also meant few people were killed. Had the explosion occurred over Moscow or London, millions would have died within minutes, making this a very serious threat indeed. Still, the immediate effect from the explosion was localized. Probably no one more than a few dozen miles away was hurt.
    But then, not all impactors are only seventy yards across . . . and not all impacts are local.

PAIN IN THE ASTEROID
    Sixty-five million years ago, the dinosaurs had a really bad day.
    Actually, recent findings show they were having a bad couple of million years. There are indications that the Earth’s climate had been changing, and many species were already in decline. However, there is overwhelming evidence that a great number of species indeed died practically overnight on a geological time scale. It’s now a matter of scientific fact that this event was triggered by the impact of a six-mile-wide asteroid—and at that size, the word “meteoroid” is seriously inadequate.
    It was certainly large enough to do the trick. The mind boggles to think of the devastation wrought when a rock bigger than Mount Everest plummeted through the atmosphere and hit the Earth at ten miles per second. Imagine: when the surface of the asteroid contacted the ground, the far side was still sticking out above most of the Earth’s atmosphere.
    The exact energy of the impact is difficult to know, but it would have been hundreds of millions of megatons—far, far larger than the heftiest nuclear bomb ever detonated. In fact, even if you detonated every single nuclear weapon on Earth simultaneously, the explosion generated by the impact of the dinosaur killer would have been a million times more powerful . . . all concentrated in one spot.
    The dinosaurs had a really, really bad day.
    That massive impact set off a terrifying series of events, each of which brought destruction on an unimaginable scale.
    As the asteroid plunged through the air, it would have created a huge shock wave, superheating the atmosphere for miles around it. As bright as the Sun, it would have set everything underneath it aflame even before it hit. And if anything did manage to survive that terrible heat, it would then have to withstand the force of a giant shock wave slamming into it as the asteroid tore through the air during its supersonic travel.
    Being so large, the asteroid would hardly have slowed its flight or lost any mass at all before it slammed into the ground. Scientists now know that the impact point was just off the Yucatán Peninsula in Mexico. It impacted water—which isn’t too surprising, as water covers 71 percent of the Earth’s surface. A huge section of the Gulf of Mexico would have exploded into steam as the ferocious energy of the asteroid’s motion was converted to heat upon impact. In the relatively shallow water there, the asteroid still would not have slowed much before hitting the continental shelf. Once it finally hit rock, the impacting mass would have stopped, and the remaining energy would have flash-converted to heat.

    Meteor Crater, in Arizona, formed in an impact about 50,000 years ago. The iron asteroid that gouged this crater out of the desert was only 50 yards across. The far rim wall is almost a mile away; note the people in the lower right for scale.
     
    PHOTO BY THE AUTHOR
    At this point, what was moments before a horrifying scenario turns into complete apocalypse as several events occur at once. Slamming into the Earth’s crust, all those millions of megatons of energy exploded outward, sending molten rock and vaporized seawater upward and outward. The