SolarExplorer
Yellow Dwarf

The Sun

Also referred to as "Sol", the Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core.

Equatorial Diameter

1.39 million km

Surface Temperature

5,505°C

Rotation Period

25 Days (at equator)

Mass

$1.99 \times 10^{30} \text{ kg}$

Mean Distance from Earth

149.6 million km (1 AU)

Surface Gravity

$274 \text{ m/s}^2$

Galactic Orbit Period

225 million years

Age

~4.6 Billion Years

Luminosity

$3.8 \times 10^{26}$ Watts

The Sun's Structure

The Sun is composed of several layers, each with distinct characteristics. The interior is divided into three main zones: the Core, the Radiative Zone, and the Convective Zone. The Core is the Sun's powerhouse, where 99% of its energy is generated through nuclear fusion. This energy is transported outward first by photons in the Radiative Zone, and then by the churning motion of hot plasma in the Convective Zone.

The visible surface is the Photosphere. Above it lies the Sun's atmosphere, which consists of the Chromosphere and the vast, super-heated Corona. The Corona extends millions of kilometers into space and, paradoxically, reaches temperatures of up to 2 million °C, far hotter than the surface below it.

Scientific Discoveries

  1. The Sun's mass accounts for some 99.86% of the total mass of the Solar System.
  2. Light from the Sun takes about 8 minutes and 19 seconds to reach the Earth.
  3. The Sun exhibits differential rotation, meaning it rotates faster at its equator (about 25 days) than at its poles (about 35 days).
  4. A continuous stream of charged particles, known as the solar wind, flows from the Corona. This wind creates a giant protective bubble around the solar system called the heliosphere.
  5. The Sun is considered to be brighter than about 85% of the stars in the Milky Way galaxy.
  6. It is located about two thirds of the way out from the centre of the Milky Way.
  7. The Sun has an 11-year cycle of activity, characterized by the rise and fall of sunspots, which are temporary dark patches on the surface caused by intense magnetic fields.
  8. Eventually, in about 5 billion years, the Sun will exhaust the hydrogen in its core and expand to become a red giant, engulfing the inner planets.