Gustav Robert Kirchhoff [1824-1887]

German physicist, who was appointed professor at Heidelberg University in 1854. There, working with Robert Bunsen, he invented the technique of spectroscopy. Using this technique, Kirchhoff and Bunsen discovered the elements caesium and rubidium in 1861. Kirchoff, working alone, also discovered several elements in the sun, by investigating the solar spectrum. He is also known for his work on thermal radiation and on networks of electrical wires (see Kirchhoff's laws).