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.