January 31, 1917 - Lise Meitner and Otto Hahn discover a radioactive element called protactinium

Otto Hahn and Lise Meitner discovered a radioactive element called proactinium.

Lise Meitner was an Austrian physicist who researched radioactivity and nuclear physics. Meitner was an important part of the team that discovered nuclear fission, an achievement for which her colleague Otto Hahn received the Nobel Prize.

She is often considered one of the most blatant examples of scientific breakthroughs made by women and overlooked by the Nobel committee. A study published in 1997 in the journal Physics Today concluded that Meitner's omission was "a rare example in which negative personal opinions led to the exclusion of a deserving scientist".

Element 109, meitnerium, was named in his honor.