Helium was discovered by Pierre Janssen on 18th August 1896. The French astronomer was observing the solar eclipse at Guntur (now in Andhra Pradesh, India) and noted bright lines in the spectrum of the solar chromosphere. This meant the chromosphere is gaseous. A bright yellow line in the spectrum which had a wavelength of 587.49 nm was also recorded. Though not immediately studied, the line proved to be of helium, an element not known to exist on earth. This was the first time an element, which wasn’t known to occur on earth, was discovered on an extra-terrestrial body.
