Portal:History of science/Selected anniversaries/February 21
- 1788 - Death of Johann Georg Palitzsch, German astronomer (b. 1723)
- 1804 - The first self-propelling steam locomotive makes its outing at the Pen-y-Darren ironworks in Wales
- 1893 - Thomas Edison receives two U.S. patents for a "Cut Out for Incandescent Electric Lamps" and for a "Stop Device"
- 1895 - Birth of Carl Peter Henrik Dam Danish biochemist, Nobel laureate (d. 1976)
- 1901 - Death of George Francis FitzGerald, Irish mathematician (b. 1851)
- 1926 - Death of Heike Kamerlingh Onnes, Dutch physicist, Nobel Prize laureate (b. 1853)
- 1938 - Death of George Ellery Hale, American astronomer (b. 1868)
- 1947 - In New York City, Edwin Land demonstrates the first "instant camera", the Polaroid Land Camera, to a meeting of the Optical Society of America
- 1953 - Francis Crick and James D. Watson discover the structure of the DNA molecule
- 1999 - Death of Gertrude B. Elion, American scientist, recipient of the Nobel Prize in Physiology or Medicine (b. 1918)
- 2002 - Death of Harold Furth, Austrian-born physicist (b. 1939)