Sputnik I, the world's first artificial satellite, was launched by the Soviet Union on Oct. 4, 1957. It was 22.8 inches in diameter, weighed 183.9 pounds and took about 98 minutes to orbit the earth. The satellite had four radio antennas for broadcasting radio pulses.
A month later, the Soviet Union launched Sputnik II, which carried a heavier payload and included a dog named Laika. The launch of the Sputnik satellites had a big impact on the American space program. It lead to an increase in funding for rocket and satellite research, and inspired the creation of the National Aeronautics and Space Administration (NASA).