Celebrated for his contributions to physics and astronomy.
As an astronomer, Arago is remembered as the discoverer of the solar chromosphere and for his accurate measurements of the diameters of the planets.
In physics, his principle work was in electromagnetism and in light. In 1820 he found that iron placed in a wire coil could be magnetized by the passage of current from either a Leyden jar or a voltaic cell. In 1824 he discovered the phenomenon of magnetic rotation, in which a rotating copper disk deflects a magnetic needle suspended above it. Arago's researches in light commenced with his discovery of chromatic polarization in 1811.