Soviet Union Launches Sputnik 1 -- First Artificial Satellite

The Soviet Union launched Sputnik 1, the first artificial satellite, into low Earth orbit aboard an R-7 rocket from the Baikonur Cosmodrome. The 83.6-kilogram sphere transmitted radio pulses for 21 days and orbited Earth for three months before reentering the atmosphere. The launch marked the beginning of the Space Age and triggered the U.S.-Soviet space competition.