1896: Radioactivity is discovered accidentally by French physicist Antoine Becquerel.

Becquerel was investigating German colleague Wilhelm Roentgen’s work on phosphorescence in uranium salts when he made his discovery. Conducting an experiment using photographic plates, Becquerel found that the plates were already fully exposed before being subjected to bright sunlight. After further investigation, he concluded that the fluorescent mineral wrapped with the plates in thick black paper emitted its own nuclear radiation.

Radioactivity is triggered by the spontaneous disintegration of atomic nuclei, resulting in radiant energy in the form of alpha, beta or gamma rays.

Becquerel, the scion of a distinguished scientific family, shared the 1903 Nobel Prize in Physics with Pierre and Marie Curie for their combined work in the field of radioactivity. He was also elected permanent secretary of the Academie des Sciences in 1908, the year he died.

Source: Nobelprize.org, Wikipedia

This article first appeared on Wired.com March 1, 2007.

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