What is the main element in the Sun by mass?

Hydrogen is the main element in the Sun by mass, making up roughly 73–75% of its mass. Helium is second at about 24%, while all heavier elements together account for less than 2%.

This composition reflects both the Sun’s birth and its ongoing energy production. The Sun formed about 4.6 billion years ago from a collapsing cloud of gas and dust. Most of the cloud’s material collected in the center, where gravity produced the pressure and temperature needed for nuclear fusion.

In the core, hydrogen nuclei fuse into helium. About 600 billion kilograms of hydrogen are fused every second, and roughly 4 billion kilograms of mass are converted into energy. That energy eventually travels outward and powers the sunlight received by Earth.

A common mix-up is to confuse the most abundant element with the element currently being produced. Hydrogen dominates the Sun’s mass, but fusion steadily increases the amount of helium in the core. Astronomers also call elements heavier than helium “metals,” even though many are not metals in the everyday sense.