The Soviet Union successfully launched the Sputnik 1 satellite on Oct. 4, 1957, surprising the world and kicking off the space race. This was the first human-made satellite. Its name means "traveling companion" in Russian.
Sputnik was in the form of a sphere, 23 inches (58 centimeters) in diameter and pressurized with nitrogen.
This exploded view of the Sputnik 1 satellite reveals what its insides look like.
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