Sputnik 1 was the first man-made object ever to leave the Earth's atmosphere. The Soviet Union launched the satellite into an elliptical low Earth orbit on 4 October 1957. It was a 58 cm diameter polished metal sphere, with four external radio
antennas to broadcast radio pulses. The launch ushered in new political, military, technological and scientific developments. The satellite travelled at around 29,000 km per hour, taking 96.2 minutes to complete each orbit of the Earth. The radio signals continued for 21 days until the transmitter batteries ran out
on 26 October. Sputnik burned up on 4 January 1958 while re-entering Earth's atmosphere after three months, 1440 completed orbits of the Earth and a distance travelled of about 70 million km.