Sun is the star at the center of the Solar System. It is a nearly spherical body of extremely hot plasma composed primarily of hydrogen and helium. The Sun is the main source of light and heat for Earth and provides most of the energy that supports life on the planet.
The Sun formed approximately 4.6 billion years ago from the gravitational collapse of a region within a large cloud of gas and dust. It is classified as a G-type main-sequence star and generates energy through nuclear fusion in its core, where hydrogen nuclei are converted into helium. The energy produced in the core eventually reaches the surface and is released into space as electromagnetic radiation.
The visible surface of the Sun is called the photosphere. Above it are the chromosphere and corona, while the interior consists of the core, radiative zone, and convection zone. The Sun's surface is marked by phenomena such as sunspots, solar flares, and prominences. The Sun also produces a continuous flow of charged particles known as the solar wind.
The Sun's gravity keeps the planets, dwarf planets, asteroids, comets, and other objects in orbit around it. Its energy drives many processes on Earth, including weather, climate, and photosynthesis. Variations in solar activity can also affect Earth's magnetosphere and produce phenomena such as auroras.
The Sun is currently about halfway through its main-sequence lifetime. In several billion years, it is expected to exhaust most of the hydrogen in its core and expand into a red giant. It will eventually shed its outer layers and leave behind a dense white dwarf.