Janssen is often jointly credited with detecting the element, along with Norman Lockyer. Pogson, and Lieutenant John Herschel, and was subsequently confirmed by French astronomer Jules Janssen. Helium was first detected as an unknown, yellow spectral line signature in sunlight during a solar eclipse in 1868 by Georges Rayet, Captain C. Large amounts of new helium are created by nuclear fusion of hydrogen in stars.
The most common isotope of helium in the universe is helium-4, the vast majority of which was formed during the Big Bang. This helium-4 binding energy also accounts for why it is a product of both nuclear fusion and radioactive decay. Its abundance is similar to this in both the Sun and Jupiter, because of the very high nuclear binding energy (per nucleon) of helium-4, with respect to the next three elements after helium. It is present at about 24% of the total elemental mass, which is more than 12 times the mass of all the heavier elements combined. It is the second-lightest and second most abundant element in the observable universe, after hydrogen. Its boiling point is the lowest among all the elements, and it does not have a melting point at standard pressure. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table. Helium (from Greek: ἥλιος, romanized: helios, lit.'sun') is a chemical element with the symbol He and atomic number 2.
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