Which was the first satellite sent into space?

Sputnik was the first satellite sent into space. The Sputnik program is the commonly known name of a group of various robotic spacecraft missions launched by the Soviet Union. The first of these, Sputnik 1, launched the first human-made object to orbit the Earth. That launch took place on October 4, 1957 as part of the International Geophysical Year and demonstrated the viability of using artificial satellites to explore the upper atmosphere.