Anders Jonas Ångström

Anders Jonas Ångström was born in Sweden on 13 August 1814. He built a career studying light, heat, magnetism, and the aurora borealis, but his sharpest work came in optics. In 1852 he published Optiska undersökningar, where he formulated a law of absorption — later reworked and credited to Kirchhoff as the law of thermal radiation. Spectroscopy, the field he helped found, let scientists split light into its components and read the fingerprints of elements. He died on 21 June 1874, leaving a method that would outlast him and a unit — the ångström — that still measures wavelengths and atomic di…