October 4, 1957. On this date, the Soviet Union launched Sputnik I, the first artificial satellite to orbit the Earth. According to many space historians, the Space Age began on this date.
It was a polished metal sphere, made of aluminum alloy. It was 58 centimeters (23 inches) in diameter – about the size of a beach ball – and weighed just 184 pounds. Its four external radio antennae were meant to broadcast radio pulses. And broadcast they did. For 21 days in 1957, people around the globe heard Sputnik’s unassuming beep beep on the radio.
Want to hear it? Check out the video below.
The pressurized sphere had five primary science objectives: test a process for placing an artificial “moon” into Earth orbit; provide information on the density of Earth’s atmosphere, calculated from Sputnik’s lifetime in orbit; test radio and optical methods of orbital tracking; determine the effects of radio wave propagation though Earth’s atmosphere; and check principles of pressurization that could be used on Earth-orbiting satellites. Clearly, the next step was to place living things in space.
Sputnik’s beeping was a symbol not only of Soviet Russia’s remarkable accomplishment, but also of what many immediately assumed was Russia’s superiority in space. The American public feared that the Soviets’ ability to launch satellites also translated into the capability to launch ballistic missiles that could carry nuclear weapons from Europe to the U.S.
Then the Soviets struck again. On November 3, 1957, they launched Sputnik II, this time carrying a much heavier payload, including a dog named Laika.
Sputnik I and Sputnik II sent shockwaves around the world. American political leadership scrambled to catch up. Ultimately, that extra push resulted in the United States sending the first astronauts to walk on the moon, on July 20, 1969.
Bottom line: On October 4, 1957, the Soviet Union launched the Sputnik 1 satellite into Earth orbit, and the Space Age began. Hear the sound of Sputnik in orbit, in this post.
Eleanor Imster has helped write and edit EarthSky since 1995. She was an integral part of the award-winning EarthSky radio series almost since it began until it ended in 2013. Today, as Lead Editor at EarthSky.org, she helps present the science and nature stories and photos you enjoy. She also serves as one of the voices of EarthSky on social media platforms including Facebook, Twitter and G+. She and her husband live in Tennessee and have two grown sons.