June 5: World Environment Day
- 1553 - Birth of Bernardino Baldi, Italian mathematician (d. 1617)
- 1656 - Birth of Joseph Pitton de Tournefort, French botanist (d. 1708)
- 1716 - Death of Roger Cotes, English mathematician (b. 1682)
- 1757 - Birth of Pierre Jean George Cabanis, French physiologist (d. 1808)
- 1760 - Birth of Johan Gadolin, Finnish scientist (d. 1852)
- 1819 - Birth of John Couch Adams, English mathematician and astronomer (d. 1892)
- 1862 - Birth of Allvar Gullstrand, Swedish ophthalmologist and Nobel Prize laureate (d. 1930)
- 1883 - Birth of John Maynard Keynes, English economist (d. 1946)
- 1900 - Birth of Dennis Gabor, Hungarian physicist, Nobel Prize laureate (d. 1979)
- 1977 - The Apple II, the first practical personal computer, goes on sale.
- 1981 - The Morbidity and Mortality Weekly Report of the Centers for Disease Control and Prevention report that five homosexual men in Los Angeles, California have a rare form of pneumonia seen only in patients with weakened immune systems, in what turns out to be the first recognized cases of AIDS.
- 1995 - Bose-Einstein condensate is first created.
