The Sun's Primary Elemental Makeup
The Sun is predominantly composed of two light elements: hydrogen and helium. Approximately 73% of the Sun's mass consists of hydrogen, and about 25% is helium. The remaining 2% includes trace amounts of heavier elements, often referred to by astronomers as 'metals,' such as oxygen, carbon, neon, iron, and nitrogen.
Layers and State of Matter
Due to the extreme temperatures and pressures in its core, the matter within the Sun exists in a plasma state, where electrons are stripped from atomic nuclei. The Sun has distinct layers, including the core, radiative zone, and convective zone in its interior, surrounded by the atmosphere layers of the photosphere, chromosphere, and corona. Each layer maintains its high-temperature plasma state, although density and temperature decrease outwards.
Energy Production through Nuclear Fusion
The vast amount of energy radiated by the Sun originates from nuclear fusion reactions occurring in its core. Here, hydrogen nuclei (protons) fuse together to form helium nuclei, releasing enormous quantities of energy in the process. This specific type of fusion, primarily the proton-proton chain reaction, converts a tiny fraction of mass into energy, as described by Einstein's famous equation E=mc².
Significance of Solar Composition
The Sun's composition is crucial because it dictates its energy generation, lifespan, and overall stability. The abundance of hydrogen provides the fuel for ongoing fusion, while helium is the primary product. The equilibrium between the outward pressure from fusion and the inward pull of gravity, sustained by this composition, keeps the Sun stable, providing the consistent light and heat essential for life on Earth.