1782 - John Goodricke[?] notices that the brightness variations of Algol are periodic and proposes that it is partially eclipsed by a body moving around it
1964 - Subrahmanyan Chandrasekhar and Richard Feynman develop a general relativistic theory of stellar pulsations and show that supermassive stars are subject to a general relativistic instability
... followed by 100,000 Japanese troops.
April 30 - Louisiana Purchase Exposition World's Fair opens in Saint Louis, Missouri (closes December 1)
November - Theodore ...