Sputnik 1, launched on Oct.4, 1957, became the first artificial satellite to successfully orbit the Earth. It was a metallic sphere about 2 feet across, weighing 184 lbs (84 kg), with long "whiskers" pointing to one side, and stayed in orbit for 6 months before falling back to Earth. Its rocket booster, weighing 4 tons, also reached orbit and was easily visible from the ground.