Pierre Jules CÚsar Janssen (1824-1907)
French astronomer, was born in Paris, in February 22nd 1824, and died in Meudon, in December 23rd 1907.
Was teacher of Mathematics and Physics and was appointed correspondent to India in order to observe the total Sun eclipse in 1868. His first contribution was the proof, using a spectroscope, that the solar prominences are gaseous. He also discovered the chromosphere, a type of gaseous envelope of the Sun. The French government appointed him director of the Astrophysics Observatory in Meudon, France, where he stood for about 30 years. Janssen studied mainly the Sun, publishing an atlas with almost 6000 pictures of its surface.