The 184-pound sphere only had a diameter of almost two feet but made the United States realize the Soviets were technologically superior. It spawned the massive U.S. effort that culminated in Neil Armstrong setting foot on the moon 12 years later.

The Sputnik launch caught the United States by surprise. The Americans had been working on launching a satellite the following spring as part of Project Vanguard. But the Soviet device was eight times heavier than the American satellite, which meant the Soviets had developed advanced rockets that might be able to deliver nuclear warheads.

The Soviet Union used the launch to promote itself and, according to an article in the New York Times on Oct. 5, 1957, said people could now see how "the new socialist society" had turned the boldest dreams of mankind into reality.

Little detailed information was released by the Soviets at the time of the launch. Since then, historians have learned that Soviet Premier Nikita Khrushchev agreed to the launch after lobbying by Sergei Korolev, the chief designer of the first Soviet ICBM, and after the R-7 missile scored only one successful flight after a series of failures.

Marshall Nedelin, who supervised the Soviet ICBM program for the Soviet military, was quoted as saying that the R-7 missile should undergo further testing before it was used for such an "insignificant experiment" as the launch of Sputnik.

Sputnik traveled 500 miles above the earth at 18,000 miles-per-hour and circled the globe in 96 minutes. The satellite had two radio transmitters that sent signals even amateur radio operators could pick up.

Sputnik 1 lasted six months in space before falling back into the atmosphere.

Three Sputniks followed, two of which reached orbit. The second Sputnik was launched on Nov. 3, 1957 and carried a dog, Laika, into space. The last Sputnik was launched May 15, 1958 and remained in orbit for nearly two years.