Portal:History of science/Selected anniversaries/October 3
- 1802 – Birth of John Gorrie, American scientist (d. 1855)
- 1891 – Death of Édouard Lucas, French mathematician (b. 1842)
- 1904 – Birth of Charles J. Pedersen, American chemist, Nobel Prize laureate (d. 1989)
- 1944 – Birth of Pierre Deligne, Belgian mathematician
- 1962 - Project Mercury: Sigma 7 is launched from Cape Canaveral, with Astronaut Wally Schirra aboard, for a six-orbit, nine-hour flight
- 1986 - TASCC, a superconducting cyclotron at the Chalk River Laboratories, is officially opened
- 2006 – Death of John Crank, British mathematician (b. 1913)