Portal:History of science/Selected anniversaries/September 28
- 1605 - Birth of Ismaël Bullialdus, French astronomer (d. 1694)
- 1694 - Death of Gabriel Mouton, French scientist (b. 1618)
- 1852 - Birth of Henri Moissan, French chemist, Nobel Prize laureate (d. 1907)
- 1889 - The first General Conference on Weights and Measures (CGPM) defines the length of a meter as the distance between two lines on a standard bar of an alloy of platinum with ten percent iridium, measured at the melting point of ice
- 1895 - Death of Louis Pasteur, French scientist (b. 1822)
- 1928 - Sir Alexander Fleming notices a bacteria-killing mold growing in his laboratory, discovering what later became known as penicillin
- 1979 - Death of John Herbert Chapman, Canadian physicist (b. 1921)