Jules Janssen was a French astronomer born on February 22, 1824, in Paris. He is best known for his pioneering work in spectroscopy, which is the study of the interaction between light and matter. Janssen's research significantly advanced the understanding of solar phenomena, particularly through his observations of the solar spectrum. In 1868, Janssen made a notable discovery during a solar eclipse, identifying the element helium in the Sun's atmosphere. This was the first time helium was detected anywhere, leading to its eventual identification on Earth. His contributions laid the groundwork for future studies in both astronomy and astrophysics.