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