Yuri Gagarin
Yuri Gagarin This photo released by TASS in April 1961 shows cosmonaut Maj. Yuri Gagarin during training. The originally black-and-white photo has been colorized. AP Photo / TASS / Mattias Malmer

Original AP caption: "This photo released by TASS in April 1961 shows cosmonaut Maj. Yuri Gagarin during training. It was the Soviet Union's own giant leap for mankind -- one that would spur a humiliated America to race for the moon. It happened on Tuesday, April 12, 1961 when the air force pilot became the first human in space. (AP Photo/TASS) AP1963"

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