Helium was first discovered in the corona surrounding the Sun and later found in gases leaking from Mount Vesuvius. It is the second-most abundant element in the universe.
The first evidence of helium was observed on 18 August 1868, in the spectrum of the chromosphere of the Sun. It was discovered on Earth much later. Italian physicist Luigi Palmieri detected helium on Earth for the first time through its spectral line in 1881. He found it while analysing a material that had sublimated during a recent eruption of Mount Vesuvius. The first person to isolate helium on Earth was the Scottish chemist, Sir William Ramsay. On 26 March 1895, he heated a mineral called cleveite, which contains uranium and discovered that it gave off a gas. The gas was identified by the yellow line in its spectrum, which matched that of the helium in the Sun.
The same year, chemists Per Teodor Cleve and Abraham Langlet in Uppsala, Sweden collected enough helium to determine its atomic weight accurately. Later, Ramsay and a British chemist Frederick Soddy discovered that helium is produced whenever radioactive elements decay.
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