The Sun is the central star of the Solar System and the primary source of light, heat, and energy for Earth and the other planets. It is a nearly perfect sphere of hot plasma, composed primarily of hydrogen and helium, undergoing nuclear fusion at its core. As the closest star to Earth, the Sun plays a vital role in sustaining life and driving planetary climate, weather, and orbital dynamics.
1 General Properties
| Property | Value |
|---|---|
| Type | G-type main-sequence star (G2V) |
| Diameter | ~1,392,700 km |
| Mass | ~1.989 × 10³⁰ kg (about 99.86% of Solar System mass) |
| Surface Temperature | ~5,778 K (~5,505 °C) |
| Core Temperature | ~15 million K |
| Distance from Earth | ~149.6 million km (1 AU) |
| Age | ~4.6 billion years |
| Rotation Period | ~25 days (equator), ~35 days (poles) |
| Luminosity | ~3.828 × 10²⁶ W |
2 Structure
The Sun is composed of several distinct layers:
- Core – where nuclear fusion occurs, producing vast amounts of energy
- Radiative Zone – energy travels slowly outward via radiation
- Convective Zone – energy is transported by convection currents
- Photosphere – the visible "surface" of the Sun
- Chromosphere – a thin, irregular layer of glowing gas above the photosphere
- Corona – the outermost atmosphere, extending millions of kilometers into space and visible during solar eclipses
3 Composition
- ~74% Hydrogen, ~24% Helium, and trace elements such as oxygen, carbon, neon, and iron
- The Sun fuses hydrogen into helium in its core through nuclear fusion, releasing energy that radiates outward as sunlight