Sputnik was the first artificial SATELLITE to be launched into Earth's orbit in 1957 by the Soviet Union. It was a 58 cm diameter metal sphere that weighed around 83 kg and orbited the Earth at a height of 900 km. The SATELLITE was powered by two radio transmitters that broadcasted signals back to Earth, allowing scientists to track its path. Sputnik's launch marked the beginning of the space race between the United States and the Soviet Union.