Nuclear fission of heavy elements was discovered on December 17, 1938 by German Otto Hahn and his assistant Fritz Strassmann, and explained theoretically in January 1939 by Lise Meitner and her nephew Otto Robert Frisch.
Kernefission af tunge grundstoffer blev opdaget 17. december 1938 af tyskeren Otto Hahn og hans assistent Fritz Strassmann, og forklaret teoretisk i januar 1939 af Lise Meitner og hendes nevø Otto Robert Frisch.