Final answer:
Sputnik, the world's first artificial satellite, was launched by the Soviet Union in 1957, leading to the space race and influencing military strategies during the Cold War.
Step-by-step explanation:
The launch of Sputnik by the Soviet Union on October 4, 1957, marked a significant milestone in the space race, signaling the start of a new era in space exploration and military technology. Sputnik was not only the world's first artificial satellite to orbit the Earth, but it also represented the Soviet's early lead in the emerging space race - a competition primarily between the Soviet Union and the United States. The success of Sputnik directly spurred the US to enhance its own space program, leading to greater efforts that ultimately resulted in the creation of NASA and the eventual success with Explorer 1.
The impact of Sputnik extended beyond immediate scientific achievement; it had military implications since the technology used to launch it was also applicable to intercontinental ballistic missiles (ICBMs). The political and military concerns of the United States following the launch of Sputnik contributed to the atmosphere of the cold war and the perennial fear that the Soviets had the upper hand in missile technology. This event significantly contributed to changing the strategic dynamics of the Cold War and the technological competition between the superpowers of that era.