Named for the French physicist Henri Becquerel {1852–1908} on the centennial of his discovery of radioactivity in March 1896. Becquerel’s work led to the discovery of radium, nuclear transmutation and nuclear fission, and it has had a myriad applications in medicine, the sciences and industry. Radionuclides are used in diagnosis (nuclear medicine), therapy and research. Radiodating has revolutionized geology, archaeology, anthropology and history. Radioactivity explains how the earth has stayed warm; nuclear reactions explain how the sun and other stars maintain their immense energy output. (M 27332; M 27347) _ _.