text: It was discovered in 1911 , as a result of Ernest Rutherford 's interpretation of the famous 1909 Rutherford experiment performed by Hans Geiger and Ernest Marsden , under the direction of Rutherford .
simplified: Around the same time that this was happening ( 1909 ) Ernest Rutherford performed a remarkable experiment in which Hans Geiger and Ernest Marsden under his supervision fired alpha particles ( helium nuclei ) at a thin film of gold foil .