The Sun is the star at the center of our Solar System, and is the most important source of energy for life on Earth. It is a nearly perfect sphere of hot plasma, with internal convective motion that generates a magnetic field via a dynamo process. Its diameter is about 1.39 million kilometers, making it about 109 times wider than Earth. It has a mass of about 2×10^30 kilograms, which accounts for about 99.86% of the total mass of the Solar System.

The Sun is composed of roughly 70% hydrogen and 28% helium by mass, with much smaller quantities of heavier elements. The remaining 1.5% of the Sun's mass consists of heavier elements including oxygen, carbon, neon, and iron, among others.

The Sun's core is the hottest part of the Sun, reaching temperatures of 15 million Kelvin. The core is where nuclear fusion reactions take place, releasing energy in the form of gamma rays. This energy travels outward through the radiative zone and the convective zone, before eventually reaching the photosphere, where it escapes into space as visible light.

The Sun's atmosphere is divided into several layers. The uppermost layer is the photosphere. This is the layer we can see