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
... Prize
April 16 - Fifi D'Orsay, actress (+ 1983)
April 22 - Robert Oppenheimer, physicist (+ 1967)
May 6 - Harry Martinson, swedish author, winner of the Nobel Prize ...