Space is an exceedingly random place. Everything in the known universe may be governed by some pretty hard laws of physics, but so are BBs in a jar when you shake them up and down. That doesn’t stop things from getting very chaotic inside. The same extreme arbitrariness is worth keeping in mind as we contemplate our planet’s close brush with an asteroid this week.
(FROM THE ARCHIVES: Asteroids: Whew!)
As TIME reports in this week’s issue (available to subscribers here), astronomers have known for the better part of a year that asteroid 2012 DA14—a medium sized, 150 ft (50 m) rock weighing 143,000 tons—was closing in on us. They knew that it would miss us too, by 17,200 miles (27,700 km). That seems like a big number, but in a solar system measured in billions of miles and a universe measured in billions of light years, it vanishes to inconsequence. The fact is, the odds of our getting clobbered by the rogue rock were in some ways the same as its missing us—at least when you fold into the equation how little it would have taken to change both its course and its impact. So what would those x-factors have been that would have turned a near miss into a true disaster, and what would the nastiness that resulted have looked like?
et’s start by making 2012 DA14 bigger—though it hardly needs the extra
bulk. At its current size, it would produce a blast equivalent to 2.4
megatons, or 180 Hiroshimas, after it entered our atmosphere. A
significantly bigger asteroid would produce a significantly bigger blast
and there’s no shortage of those cosmic missiles out there. Astronomers
estimate there are 2,400 objects in the vicinity of Earth
that are at least 0.5 km (0.3 mi) across and 860 of those are a full 1
km (.62 mi.). A 0.5 km rock would produce a 5,000 megaton blast—not to
mention a 7.1 Richter-scale shock. Let’s split the difference then, but
err on the size of conservatism: Our death rock would be a comparatively
modest 100 m, or 330 ft., across.
No comments