What is the Sun primarily composed of?

The Sun is primarily composed of hydrogen and helium. These two light elements make up almost all of the Sun’s mass, with hydrogen dominant and helium second.

The Sun formed about 4.6 billion years ago from a collapsing cloud of gas and dust. Its immense gravity compressed the material until the core became hot and dense enough for nuclear fusion. In that process, hydrogen nuclei combine to form helium, releasing the energy that ultimately powers sunlight and heat.

The Sun also contains small amounts of heavier elements, including oxygen, carbon, neon, and iron. Astronomers collectively call these elements “metals,” even when they are not metallic in the everyday sense. They are important for studying the Sun’s history, but they represent only a small fraction of its composition. The Sun is therefore not primarily made of oxygen, carbon, or iron; those elements are minor ingredients compared with hydrogen and helium.