Why did a beeping metal ball shock America into the space race?

Because the object itself mattered less than what it implied. Sputnik 1 was a polished metal sphere 58 cm across with four antennas, launched by the Soviet Union on 4 October 1957 as the first artificial Earth satellite. Its radio signal was easily picked up by amateur radio operators, and its orbit carried it over virtually the entire inhabited Earth.

The surprise was not complete. President Eisenhower was not surprised by Sputnik 1: U-2 spy plane photos and signals intercepts had warned him of the R-7 rocket's capabilities. But he greatly underestimated the reaction of the American public, who were shocked by Sputnik and then by the televised failure of the Vanguard rocket. Democratic politicians inflamed the anxiety by portraying the US as woefully behind, and a "missile gap" became a dominant issue in the 1960 presidential campaign.

The panic produced institutions. Public reaction spurred the creation of ARPA, later DARPA, and NASA, and increased spending on research and education through the National Defense Education Act. A University of Michigan poll after the launch found that 26% of Americans thought Soviet science and engineering was superior; a year later, as the US launched its own satellites, the figure was 10%.