Smash Hits
There is evidence that, in the past, massive comet or asteroids have struck Earth’s surface. Thirty-five million years ago, a three-kilometer-wide (two-mile-wide) rock smashed into the ocean floor, 160 kilometers (100miles) from what is now Washington, D.C., leaving an 85-kilometers-wide (50-mile-wide) crater buried beneath Chesapeake Bay. Another giant rock, called Titan, ten kilometers (six miles) in diameter, smashed into the Gulf of Mexico around 65 million years ago, unleashing thousands of times more energy than all the nuclear weapon on the planet combined. “The whole Earth burned that day,” says Ed Lu, a physicist and former astronaut. The chaos and devastation were unimaginable. Three-quarters of all life forms, including the dinosaurs, went extinct.