Layers
The outermost layer of the Sun’s atmosphere is the corona.
The corona extends outward from the sun to the edge of the solar
system in the form of “solar wind” (3). The temperature
of the particles in the corona can reach temperatures of up to
1,700,000° C. These particles, however, are spread very far
apart from each other (1). The process that heats the corona is
not known very well, for the laws of thermodynamics state that
heat flows from hotter to cooler areas, which does not
necessarily happen in the corona (3).
Beneath the corona is the chromosphere. It is several thousand
kilometers thick (up to 16,000 with solar flares) and can reach
temperatures of around 27,800° C (1). The chromosphere may be
seen briefly as a reddish rim during a solar eclipse.
The photosphere is known as the “surface” of the Sun,
the innermost layer of the Sun’s atmosphere. It is about 500
km thick and is where most of the Sun’s radiation and light
escape into the solar system (3). The temperature of the
photosphere is about 6000°C. (1), and is the place on the sun
where sunspots are found (3).
The interior of the Sun is called the core. It is here where the
hydrogen atoms are fused into helium (1), releasing heat and
light that take around 10 million years to reach the Sun’s
surface (3). This energy that is released prevents the collapse
of the Sun and keeps it in gaseous form (3). The total energy
radiated is equivalent to that generated by 100 billion tons of
TNT exploding every second (3).