The Soviet Union was the first country to launch an artificial satellite, sending Sputnik 1 into orbit on 4 October 1957. The launch took place from the Baikonur Cosmodrome in the Kazakh Soviet Socialist Republic.
Sputnik 1 was a polished metal sphere about 58 centimetres in diameter with four radio antennas. It transmitted simple radio signals that could be detected on Earth, demonstrating that the Soviet Union had reached orbit and could track an object in space.
The satellite orbited Earth approximately every 96 minutes. It remained in space for about three months before atmospheric drag caused it to re-enter and burn up on 4 January 1958.
Sputnik 1 began the Space Age and intensified the Cold War space race. The United States responded with its own satellite, Explorer 1, launched on 31 January 1958. Explorer 1 carried scientific instruments that discovered the Van Allen radiation belts.