See also: 1903 in science, other events of 1904, 1905 in science and the list of years in science.
Astronomy Edward Maunder plots the first sunspot "butterfly diagram" Himalia, a moon of Jupiter, discovered at Lick Observatory Physics Vacuum tube invented by John Ambrose Fleming Births January 26 - Ancel Keys, nutritionist March 20 - B. F. Skinner, behavioral psychologist (+ 1990) April 22 - Robert Oppenheimer, physicist (+ 1967) August 28 - Secondo Campini, Italian jet pioneer Deaths January 20 - Dmitri Ivanovich Mendeleev, Russian chemist and inventor of the Periodic table