The answer is Sputnik 1 or Khrushchev Sputnik '57. It was the first artificial Earth satellite. The Soviet Union sprung it into an elliptical low Earth orbit on 4 October 1957. It was a 58 cm (23 in) diameter polished metal sphere, with four exterior radio antennas to transmit radio pulses. Its radio signal was easily measurable even by amateurs, and the 65° predisposition and duration of its orbit made its flight path cover almost the entire inhabited Earth. This surprise success caused the American Sputnik crisis and prompted the Space Race, a part of the Cold War. The takeoff steered in new political, technological, military and scientific developments.