We’re safe. Comet Swift-Tuttle won’t collide with Earth on its next foray into the inner solar system in 2126. More good news: pieces of the comet will smash into our planet this month.
To many of us, comet fragments are old friends. I remember my summer campmates excitedly gathering at the lakeside for the annual Perseid meteor shower. Cheering each shooting star, we didn’t realize that the speeding sky-pebbles had fallen off a passing comet like feathers from a startled goose. Astronomers know that the August meteors are pieces of Swift-Tuttle, left in its wake and traveling in the same orbit. Until last year, however, no one knew just when the comet itself would show its face again.
It had last been seen in the mid-nineteenth century. With an uncertain orbital period, the comet could stay away indefinitely. The best calculations suggested it might reappear around 1981. It didn’t. But ...
