A Groundbreaking Discovery

On November 8, 1895, physicist Wilhelm Conrad Roentgen was experimenting with cathode rays—streams of electrons that were first observed in 1859 by two other German physicists, Julius Plücker and Johann Wilhelm Hittorf. During his experiment, he noticed a glow appear on a screen that was nine feet away, although he had shielded the tube he was using to produce the rays with thick black cardboard. Investigation of this strange phenomenon led to the discovery of a previously unknown form of radiation that could penetrate solid objects. He named this newly discovered radiation “X-rays.”