Since the beginning of recorded history, people have been mystified by UFOs--unidentified flying objects. Even Christopher Columbus, on a 1492 voyage aboard the Santa Maria, was puzzled by a sight he described as "a light glimmering at a great distance" in the sky. While no UFOs have ever been captured or recovered, there may be startling clues to their existence left behind in places where they are thought to have struck the ground. In this book,...