F or most of human history .People thought the world was flat. That is, they thought that if you traveled far enough in one direction, you would eventually come to the edge of the world. Then, about two thousand years ago, people started to come up with the theory ( 理论) that the earth was round. This meant that traveling far enough in a straight line, you would eventually come back to where you started. It wasn ’ t until the sixteenth century that Ferdinand Magellan ’ s expedition ( 探险) became the first to travel around the world. The expedition first sailed west from Portugal ( 葡萄牙), around South America, across the Pacific, before returning around Sound Africa back to Portugal. Although Magellan died during the trip, one of his captains, Sebastian del Cano, made it all the way. In 1872, the French author Jules Verne published a book called Around the World in 80 Days. The novel was about a man who travels around the world, starting from London, in win a bet ( 赌). In 1889, an American reporter, Nellie Bly, was sent by her newspaper to complete the journey taken by the characters in Verne ’ s book. She traveled around back home after her trip, taking 72 days, six hours, eleven minutes, and fourteen seconds to go around the world. Even though traveling around the world these days is very easy, and can be done in one or two days by plane, people are still interested in breaking records ( 打破记录). F rom 1970 to 1974, an American, Dave Kunst, was the first person to walk all the way around the world. He wore out twenty-one pairs of shoes on his trip! The first airplane flight around the world took place in 1924, completed by Lt. Lowell H. Smith and five other American pilots, and the first solo helicopter flight around the world was done by an Australian explorer, Dick Smith, in 1982-83. As for a nonstop balloon flight all the way around the world, this wasn ’ t completed until 2002, when Steve Fossett succeeded at last.