Yuri Gagarin — First Man in Space

NASA
Cosmonautics Day, celebrated on April 12, commemorates the first ever manned flight into outer space by one of the world's most timeless pioneers: Yuri Gagarin. 

In November 1957, Laika, a stray dog from Moscow, was launched into space in a 508-kilogram Sputnik-2 capsule and became the first animal to orbit the Earth. Laika's flight proved living beings could survive the conditions of outer space, but could humans undergo a similar test of endurance and live to tell the tale? 

Roughly three years after Laika's mission, on Apr. 12, 1961, the 27-year-old Russian cosmonaut Yuri Gagarin followed suit and made history as the first man to orbit the Earth. His flight lasted 108 minutes from launch to landing. 

According to NASA, the physical hazards of weightlessness at the time of Gagarin's flight were almost wholly unknown.