The Sun's Internal Divisions

The Sun’s Internal Divisions

Core

  • The core is the innermost part of the Sun where nuclear fusion occurs.
  • The density and temperature are extreme, reaching up to 15 million degrees Celsius.
  • The Sun’s core is where hydrogen atoms combine to form helium, releasing large amounts of energy in the process.
  • This energy takes the form of gamma radiation, which gradually makes its way out of the core.

Radiative Zone

  • The radiative zone surrounds the core, and is the location where energy produced in the core travels outwards.
  • This zone is so dense that photons of light can take many thousands of years to pass through it.
  • The process involves photons being absorbed and re-emitted in a random way, often referred to as a “random walk”.
  • The radiative zone extends from the core to about 70% of the way to the Sun’s surface.

Convective Zone

  • The convective zone is where the heated material from the radiative zone rises towards the Sun’s surface.
  • Here, the energy is transferred more by convection, where hot plasma rises, cools as it gets closer to the surface, and then sinks back down to collect more heat.
  • The rotating and rising cells of gas in this zone contribute to the Sun’s magnetic field.
  • The Convective Zone accounts for the outermost 30% of the solar interior.

Photosphere

  • The photosphere is the visible surface of the Sun that emits sunlight that we see from Earth.
  • This layer is relatively thin, and is the layer from which most of the Sun’s radiation and light finally escape into space.
  • The photosphere has an average temperature of about 5,500 degrees Celsius.
  • The surface shows a granulated appearance due to the tops of the convective cells appearing as bright granules.

Chromosphere

  • The chromosphere lies above the photosphere and is the second of three main layers in the Sun’s atmosphere.
  • During total solar eclipses when the Moon blocks the bright photosphere, the chromosphere can be seen as a thin red rim.
  • This layer is hotter than the photosphere but less dense.

Corona

  • The corona is the Sun’s outer atmosphere and is seen during total solar eclipses as a unique and beautiful crown of pearly light.
  • The corona is extremely hot, reaching temperatures of 1-3 million degrees Celsius, but has a low density.
  • The solar wind, a stream of charged particles, originates from this layer and extends into space in all directions.