Which country was the first to launch an artificial satellite?

The Soviet Union was the first country to launch an artificial satellite. It sent Sputnik 1 into orbit on 4 October 1957 from the Baikonur Cosmodrome in what is now Kazakhstan.

Sputnik 1 was a polished metal sphere about 58 centimetres in diameter, equipped with four radio antennae. It transmitted beeping radio signals that could be detected around the world. The satellite orbited Earth roughly every 96 minutes and remained in space for about three months before atmospheric drag caused it to re-enter.

The launch began the Space Age and intensified the Space Race between the Soviet Union and the United States. The United States launched its first satellite, Explorer 1, in January 1958. Sputnik 1 carried no people and was much simpler than later spacecraft, but its successful orbit demonstrated that a nation could place an object beyond Earth's atmosphere and track it from the ground.