Radon was first identified as a distinct radioactive gas in 1899 by Ernest Rutherford and Robert B. Owens, and its emission from radium was later studied in detail by the German chemist Friedrich Ernst Dorn in 1900. Today, Dorn is often credited with its discovery in the context of the radium decay chain, while Rutherford and Owens are recognized for first detecting the new radioactive “emanation” that became known as radon.