"It seems to me that everything that happens to us is a disconcerting mix of choice and contingency." -- Dame Penelope Lively, British author. On the morning of February 15, 2013, a fireball ripped through the sky above the Russian city of Chelyabinsk, exploding 18 miles up after leaving a streak of fire tens of miles long. The minor asteroid, which was about the size of an apartment building, was actually the second to have visited the Siberian region in a little over a century: 1908's Tunguska meteor, which was about the same size, fortunately fell to Earth in an uninhabited wilderness, blowing down and charring 800 square miles of timber. The people of Chelyabinsk were lucky, because the meteor entered the atmosphere at a shallow angle. According to modeling done by Dr. Mark … [Read more...]