Contrary to what you may have read, Earth will not be devastated by the asteroid Apophis on April 13, 2029. Neither will Bennu, a 1/3-mile-wide pile of flying space rubble, strike us on Sept. 24, 2182. Every single scare story out there warning of an impending celestial collision is just that, a scary tale. At the same time, it is inevitable that such an impact will eventually occur — and when it does, the event could generate vast firestorms, tsunamis and extinctions.
That is the asteroid paradox, explains Amy Mainzer, a planetary-defense expert at the University of Arizona’s Lunar and Planetary Laboratory: The odds of a major impact in any given year are minuscule, but the potential consequences are enormous. Further confounding things, the smaller the impact, the more likely it is to occur and the more difficult it is to predict. All those variables make it intensely challenging for scientists like Mainzer to assess asteroid risks in a useful way, and then to communicate that risk to the public. “You don't need to run out and buy asteroid insurance,” she says. “But you don't want to completely ignore the problem either.”
