Sputnik 1 was the first artificial Earth satellite. It was a 58 cm (23 in) diameter polished metal sphere, with four external radio antennas to broadcast radio pulses. The Soviet Union launched it into an elliptical low Earth orbit on 4 October 1957. It was visible all around the Earth and its radio pulses were detectable. The surprise success precipitated the American Sputnik crisis and triggered the Space Race, a part of the larger Cold War. The launch ushered in new political, military, technological, and scientific developments.