As a Delta Air Lines jet was flying over Arizona on a clear day the co-pilot was providing his passengers with a running commentary about landmarks over the PA system. ""Coming up on the right you can see the Meteor Crater which is a major tourist attraction in northern Arizona. It was formed when a lump of nickel and iron roughly 150 feet in diameter and weighing 300000 tons struck the earth at about 40000 miles an hour scattering white-hot debris for miles in every direction. The hole measu…