On July 20, 1969, the astronaut Neil Armstrong became the first human being to walk on another world. An iceberg is a large piece of freshwater ice that has broken off a glacier or an ice shelf and is floating freely in open (salt) water. A golf ball is a special ball designed to be used in the game of golf. A train is a form of rail transport consisting of a series of connected vehicles that generally run along a railway track to transport passengers or cargo.