THE STRUCTURE OF THE SUN

The Sun is not a solid object but a series of layers, each with distinct temperatures and physical properties. It is structured into the Internal Layers (where energy is created) and the Atmospheric Layers (which we can observe).
The Internal Layers
The Core:
The innermost part of the Sun, making up about 25% of its radius.
The temperature reaches 15 million°C, with extreme pressure.
This is the Sun's "engine room," where nuclear fusion occurs, turning hydrogen into helium and releasing massive amounts of energy.
Radiative Zone:
Surrounds the core and extends to about 70% of the Sun's radius.
Energy moves very slowly here through radiation.
Photons (light particles) bounce around so much in this dense layer that it can take over 100,000 years for energy to travel from the core to the next layer.
Convection Zone:
The outermost layer of the interior.
Energy is transported by convection currents—hot plasma rises, cools near the surface, and then sinks back down, similar to the movement of boiling water.
The Solar Atmosphere
Photosphere:
The visible "surface" of the Sun that we see from Earth.
It is relatively thin (about 500 km) and has a temperature of roughly 5,500°C.
This is where sunspots (cooler, darker regions) appear.
Chromosphere:
A thin, reddish layer above the photosphere.
It is only visible during a total solar eclipse or with special telescopes.
Temperatures here actually start to rise again, reaching up to 20,000°C.
Transition Region:
A very narrow, irregular layer where the temperature rises drastically from thousands to millions of degrees.
Corona:
The Sun’s outermost atmosphere, extending millions of kilometers into space.
It is incredibly hot (1 to 3 million°C), even hotter than the surface.
It is visible as a white "halo" during a solar eclipse and is the source of the solar wind.