On this day in 1957, Sputnik I became the first artificial satellite to orbit the Earth. The beachball-sized Soviet machine circled the planet in a low elliptical orbit for three weeks before its batteries finally died. Then it continued for two more months before finally falling back into the atmosphere. The unexpected success of Sputnik I triggered the great 20th Century space race between the Soviet Union and the United States. Sputnik gave the Soviets a tremendous head start, but arguably the U.S. won the race when it put the first human beings on another astronomical body—on July 20, 1969, when Apollo 11 landed on the Moon.