Portal:History of science/Selected anniversaries/June 30
- 1660 - Death of William Oughtred, English mathematician (b. 1575)
- 1709 - Death of Edward Lhuyd, Welsh scientist (b. 1660)
- 1817 - Birth of Joseph Dalton Hooker, British botanist (d. 1911)
- 1857 - Death of Alcide d'Orbigny, French naturalist (b. 1802)
- 1860 - The 1860 Oxford evolution debate at the Oxford University Museum of Natural History takes place
- 1905 - Albert Einstein publishes the article "On the Electrodynamics of Moving Bodies", in which he introduces special relativity
- 1919 - Death of John Strutt, 3rd Baron Rayleigh, English physicist, Nobel Prize laureate (b. 1842)
- 1926 - Birth of Paul Berg, Nobel Prize laureate
- 1952 - Birth of Athanassios S. Fokas, Greek mathematician
- 1972 - One leap second is added to the UTC time system, also the first