Radioactivity Discovered 110 years ago

On March 1, 1896 Henri Becquerel discovered an invisible, penetrating radiation emitted spontaneously by Uranium. He showed that these "uranic rays" made an imprint on photographic plates and made air conduct electricity.

He made the discovery when he developed the photographic plate that he left in a desk drawer and found it had fogged with the image of the uranium compound crystals resting on it. Thus, the discovery was in fact the result of a chance occurrence. He had originally stored objects together on February 26, after postponing his intended experiment on phosphorescent emissions stimulated by the sun. Instead he now found spontaneous and penetrating rays, independent of any input of energy. The mysterious nucleus of the atom had been revealed, but realizing that took more years of research by other scientists.

In 1899 E. Rutherford discovered and named alpha and beta radiation, and in 1900 P. Villard identified gamma radiation. Marie and Pierre Curie extended the work on radioactivity, demonstrating the radioactive properties of thorium and discovering the highly radioactive element radium in 1898. Frédéric and Irène Joliot-Curie discovered the first example of artificial radioactivity in 1934 by bombarding nonradioactive elements with alpha particles.

Becquerel received a share of the 1903 Nobel Prize with Pierre and Marie Curie for their work on radioactivity.

Born in Paris in 1852, Henri Becquerel became a Professor of Physics at the French Natural History Museum in Paris and at the Ecole Polytechnique. He was a specialist in phenomena related to the polarisation of light and in processes involving the luminescence of materials. The year after completing his Doctoral thesis in 1888, he was elected to the Academy of Sciences. Becquerel died in 1908.