Sputnik 1 was the first man-made object to orbit the Earth. It was launched by the Soviet Union on 4th October 1957, using an R7 rocket.
The body was 585mm in diameter, and made of highly polished alumium alloy. After 22 days orbiting the earth at an altitude of approximately 150km, the batteries were depleted, halting radio communications. It re-entered the earths atmosphere and burned up on 4 January 1958.