In 1909, not long after Thomson's model was proposed, Hans Geiger and Ernest Marsden made an experiment with thin sheets of gold, to test Thomson's model. Their professor, Ernest Rutherford, expected the results to prove Thomson correct, but their results were extremely different to what they were expecting. In 1911, Rutherford discovered that the positive charges come from tiny particles called protons, and that the protons were in a tiny center called the nucleus, and that the electrons were orbiting around the nucleus.