Three Divisions of the Sun

Core

• The core is the center of the sun and the source of all the sun's energy. It makes up 25 percent of the sun's radius. The core has an extremely high temperature of more than 15 million degrees Kelvin. The high temperature of the sun provides a large amount of thermal energy for the protons and electrons to move around very quickly. This fast motion causes the particles to crash into one another, creating nuclear fusion reactions, which provide the energy source for the sun.

Radiative Zone

• The radiative zone of the sun is the portion surrounding its core. It is the largest section of the sun, making up 45 percent of its radius. The sun transmits its energy out from its core by the process of radiation. Some atoms are able to remain intact in the radiative zone because it is much cooler than the core. The sun's energy moves outside through the interaction between these atoms in the radiative zone.

Convective Zone

• The convective zone, or convection zone, forms the outer shell of the sun, making up 30 percent of its radius. Energy is transferred much faster in the convective zone than it is in the radiative zone, because it is cooler and thus less dense. Hot gas rises from the radiative zone and moves up to the top of the convective zone, then it falls back to the bottom of the convective zone. This process repeats itself several times, creating convection currents, which look like boiling water on the sun's surface. Heat is finally released once the material reaches the top of the convection zone and cools to a sufficiently low temperature.

Photosphere

• The visible portion of the sun is called the photosphere. It is the layer above the convective zone where light is emitted. The photosphere heats up to a temperature of 6,000 degrees Kelvin. Although the photosphere does not make up one of the three divisions of the sun, it is the only portion that we can see.