Worries change though, and the discovery that a massive chunk fell out of the sky and killed the dinosaurs, plus a few Hollywood blockbusters about a fictional chonk space rock killing all of us if it wasn’t for Bruce Willis, and now there’s at least one story a week in the news about astronomers discovering another near-earth object that could potentially flatten us back into the Stone Age.
They haven’t found one that is actually going to hit our planet yet, and their definition of “near” extends out several millions of miles, but when science writers seize on each newly-discovered interplanetary brick capable of busting the windshield of human existence, the first thing they do is size it. And we’re not talking about its size in feet, yards, meters, tons or kilos. The science press is obsessed with comparing planet-popping rock gobs to objects it thinks the public can identify with.
Just go to Google and run “asteroid the size of” as a search and you’ll see what I mean. They run the gamut from “the size of a giraffe,” up to “the size of Texas.” Architectural achievements are well-represented. The Great Pyramid, the Empire State Building, the Golden Gate Bridge and the Eiffel Tower all have their asteroidal equivalents floating around out there, waiting to smush into us and cause unimaginable harm.
For some reason, giraffes are the favored animal in which to size asteroids. Asteroids the size of polar bears, elephants and blue whales must be out there as well, but so far, they remain outside of scientific scrutiny. But giraffe-sized asteroids have been spotted, raising the questions about the appearance and behavior of these space stones. Are they spotted? Do they graze on the high leaves of the solar system? Will they inevitably crash into the Serengeti?
Another Google result is “the size of 350 giraffes.” This is useless. Nobody I know has ever seen 350 giraffes at once. There is also “the size of 2,000 ferrets.” This may make sense to you, if you are concerned about asteroids and also a ferret-farmer, but it doesn’t help the rest of us much.
Some asteroids are vaguely described. The “size of a building,” is often used. Buildings can range from the size of a sex shop or a meth lab to the size of the Pentagon, and the asteroid-watching public deserves to know which variety of building is most likely to land on their head like a leftover Chinese booster rocket.
There are many objects that most people are perfectly familiar with the size of, and yet they never make it into the asteroid comparative-sizing chart. You’ll never see “The size of the yard sale my weirdo neighbors have every week,” “the size of the truck I’ve been stuck behind for five fucking minutes on this goddam upgrade,” “the size of an $800,000 condo in La Jolla, California,” or “the size of a destination wedding party on Maui,” used to describe any potential earth-ending space rubble.
Also neglected are the effects of sized asteroids. An asteroid the size of a giraffe would kill you pretty cleanly if it landed in your man cave, just as cleanly as a real giraffe would if it did the same, and a tad more explosively besides, but it wouldn’t end many lives outside of your own. An asteroid the size of the Golden Gate Bridge would blow up Marin County and a couple of adjacent counties besides, or swamp the Bay with a tsunami as tall as, say, the Eiffel Tower, if it landed in the adjacent Pacific, but it wouldn’t would wipe out life on Earth.
State-sized asteroids are of much deeper concern. An asteroid the size of Rhode Island would be massively bigger than the six-mile-wide space slab that erased the dinosaurs, so evolution might have to start over again from whatever preheated scum might survive in the oceans, if that one hit. An asteroid the size of Texas would be pretty unlikely, considering Texas is 801 miles across, and the largest known asteroid, Ceres, is only 587 miles across. But if an asteroid the size of Texas would sneak in from one of the low-rent neighborhoods that surround the Solar System, like the Kuiper Belt, it would probably blow enough of Earth into space to form a ring around it, which would eventually coalesce into a second, smaller Moon.
Which would be pretty, sure. None of us would be around to write songs about it, though.