The Madness of the Planets
I am a staunch believer in leading with the bad news, so let me get straight to the point. Earth, our anchor and our solitary haven in a hostile universe, is in a precarious situation. The solar system around us is rife with instability.
Residents of Chelyabinsk, Russia, experienced this firsthand at 9:20 a.m. local time last Feb. 15, when a 50-foot-wide asteroid slammed into Earth’s atmosphere and exploded above the town, shattering windows, collapsing the roof of a local zinc factory, and sending more than a thousand people to the hospital with glass cuts and other injuries. Millions of people saw the videos of Comet ISON meeting a different but related cataclysmic fate as it took a swan dive past the sun on Thanksgiving Day. In the space of a few hours, the 4.5-billion-year-old comet was reduced to a cloud of sputtering rubble.
But these incidents are mere pixels in the sweeping picture emerging from the latest theories of how our solar system formed and evolved. Collisions and dislocations are not occasional anomalies; they are a fundamental cosmic condition.
“Things are not as simple as they were supposed to be, with the planets staying quiet forever,” says Alessandro Morbidelli, a planetary dynamics expert at the Nice Observatory in France. “When the planets form they don’t know they have to form on good orbits to be stable for billions of years! So they are stable temporarily, but are not stable for the lifetime of the star.”
Translation: Earth was forged in chaos, lives in chaos, and may well end in chaos.
While Morbidelli is explaining all this to me in a cheery Italian accent, I cannot help fixating on the grim connotations of his last name. He and his scientific compatriots are amplifying a recent realization about our celestial home: Instability is our natural state. For centuries, Isaac Newton and his followers envisioned a solar system that runs like divine clockwork. Only in the past decade have high-precision mathematical simulations shown just how wrong he was. Carl Sagan famously declared that “we’re
