The launch of the first artificial Earth satellite, on October 4, 1957, took much of the world by surprise, but it shouldn’t have. The U.S. military had been studying the possibility of “world-circling spaceships” since shortly after World War II, and in 1955 both the United States and the Soviet Union announced the intent to orbit a scientific satellite in time for the International Geophysical Year, in 1957-1958. By then the general public was primed for the Space Age to begin, having been fed a steady diet of flying saucer movies, speculative magazine features, and accounts of real-life journeys to the stratosphere by space-suited balloonists.

Yet the exact timing of the first attempt to launch a satellite was veiled in secrecy, as both sides of the cold war focused on the real race: to design missiles with enough power to hurl nuclear bombs at each other from half a world away. The Soviets got there first, with the launch of the world’s first successful intercontinental ballistic missile, the R-7, on August 21, 1957. Six weeks later, another R-7 launched a polished aluminum sphere called Sputnik 1, weighing all of 184 pounds, into orbit.

The “Prostreishiy (simple) Sputnik (traveling companion),” or PS-1, was a hastily assembled understudy for a much larger spacecraft that had fallen behind schedule. In late 1956, worried that the Americans would beat the U.S.S.R. to the punch, Soviet rocket designer Mikhail Tikhonravov asked his boss, Sergei Korolev: “What if we make the satellite a little lighter and a little simpler?” Says historian Asif Siddiqi (see his article, below): “This single question, unassumingly raised, was the key to Soviet leadership in the Space Age.”

The beep-beep-beep of Sputnik—which was barely more than a radio transmitter with batteries—was heard by ham operators around the world, as Korolev had hoped. U.S. government officials, including President Dwight Eisenhower, had underestimated the effect a Soviet satellite would have on the public, and found themselves on the defensive, while educational reformers had new ammunition in their fight to revamp the nation’s science curriculum.

Pop culture got a new word—writer Herb Caen coined the term “beatnik” a few months later—and millions of people around the world had new reason to stare up at the sky in wonder.

Excerpted from 50 Greatest Moments of the Space Age, by the editors of Air & Space, on sale now.