Is This the End?
It’s very unlikely that a major comet will crash into the Earth—but not so unlikely that leading scientists around the world haven’t begun to plot ways to make sure it doesn’t happen, Timothy Ferris wrote, in 1997.
On learning of each new comet, astronomer Brian Marsden says to himself, "Yes, this one could hit the Earth. That's always a possibility." He enters the positions into his computer, adds the command "ORBDET"—determine orbit—and hits a key.