The observed precession in the orbit of the planet Mercury is 574.1 seconds of arc per century (relative to the International Celestial Reference Frame). According to Newtonian gravitational theory, taking account of the gravitational perturbations by the other planets (mainly Venus, Earth and Jupiter), a value of 531.6 is predicted. This anomaly of approximately 43 seconds of arc per century was first recognized by Le Verrier in 1859. The discrepancy was resolved by Einstein's general theory of relativity in 1915.
This Demonstration exaggerates the effect by making the mass of the Sun around times greater; also, you can change an orbital parameter.