What did Gustav Robert Kirchhoff stumble upon 150 years ago?

Gustav Robert Kirchhoff is, without a doubt, one of the founding fathers of electrical engineering. The two circuit laws named after him, formulated in 1845 at age 21, constitute the foundation of electric circuit theory. Most electrical engineers assume that Kirchhoff is well known because of these two laws and are unaware of his other important contributions to science. About 150 years ago in 1859, while performing an experiment with a spectroscope, Kirchhoff unexpectedly made a major discovery that brought him and his colleague Robert Wilhelm Bunsen their greatest scientific fame: the spectrum analysis. The purpose of this article is to use this special 150^th anniversary of his discovery as an opportunity to commemorate Kirchhoff´s life and bring attention to his many accomplishments.