The first artificial satellite to orbit the Earth was Sputnik 1, launched by the Soviet Union on October 4, 1957. Sputnik 1 was a sphere about 58 centimeters in diameter and weighed approximately 83.6 kilograms. It successfully transmitted radio pulses back to Earth, which scientists and the public could track, marking the beginning of the space age. Its launch sparked the space race between the United States and the Soviet Union, driving advancements in technology and space exploration. Sputnik 1 orbited the Earth for approximately three months before re-entering the atmosphere in January 1958.