On Aug. 23, 1961, NASA launched the Ranger 1 robotic spacecraft on a precursor mission to test new technologies for later ...

On Aug. 22, 1963, U.S. Air Force Captain Joe Walker flew an X-15 space plane higher than any pilot had ever flown before.

On May 29, 1919, a total solar eclipse helped to prove Albert Einstein's theory of general relativity. Einstein's theory suggested that gravity could bend light by curving the fabric of spacetime ...