Portal:History of science/Selected anniversaries/January 21
- 1814 - Death of Jacques-Henri Bernardin de Saint-Pierre, French writer and botanist (b. 1737)
- 1827 - Birth of Ivan Mikheevich Pervushin, Russian mathematician (d. 1900)
- 1882 - Birth of Pavel Florensky, Russian mathematician (d. 1937)
- 1912 - Birth of Konrad Emil Bloch, German-born biochemist, Nobel laureate (d. 2000)
- 1954 - The first nuclear-powered submarine, the USS Nautilus, was launched in Groton, Connecticut by Mamie Eisenhower, then the First Lady of the United States
- 1969 - An experimental underground nuclear reactor at Lucens Vad, Switzerland, released radiation into a cavern, which was then sealed