On the periodic table, hydrogen is the main component of the Sun by mass.
Hydrogen has the symbol H and atomic number 1. In the Sun’s core, enormous pressure and temperature allow hydrogen nuclei to fuse into helium. This nuclear fusion releases the energy that powers the Sun’s light and heat.
Hydrogen makes up roughly three-quarters of the Sun’s mass, while helium accounts for most of the remainder. The exact proportions change slowly because fusion converts hydrogen into helium in the core. The Sun is not burning hydrogen through ordinary chemical combustion; its energy comes from nuclear reactions.
Hydrogen is also the most abundant element in the universe. It is the lightest element and normally exists as diatomic H₂ gas on Earth. Helium is the Sun’s second-largest component, which is why it can be mistaken for the answer.