Who discovered nuclear fission in 1939?

The discovery of nuclear fission was a collaborative scientific achievement rather than the work of a single individual. By the end of 1938, German chemists Otto Hahn and Fritz Strassmann obtained conclusive evidence that bombarding uranium with neutrons produced barium, indicating the uranium atom had split.123

Hahn shared these findings with his longtime colleague Lise Meitner, who had fled Nazi Germany. In January 1939, Meitner and her nephew, physicist Otto Frisch, provided the theoretical interpretation of this process, which they termed "fission". Frisch subsequently informed Niels Bohr, who brought the news to the United States, triggering global scientific investigation into the phenomenon.42513

While Otto Hahn was awarded the 1944 Nobel Prize for Chemistry for the discovery, the essential contributions of Meitner and Strassmann are widely recognized, and all three were later honored with the Enrico Fermi Award in 1966.25