RADIATIVE ZONE

The region surrounding the solar core where energy travels outward primarily through the diffusion of photons.

RADIATIVE ZONE · ENERGY DIFFUSION

≈ 25–70%

SOLAR RADIUS

≈ 7M → 2M K

APPROX. TEMPERATURE

PHOTONS

PRIMARY ENERGY TRANSFER

HIGH

PLASMA DENSITY

RADIATION

ENERGY TRANSPORT

≈ 45%

RADIAL THICKNESS

WHAT IS THE RADIATIVE ZONE?

The radiative zone extends outward from approximately 25% to 70% of the Sun's radius. Unlike the convective zone, material in this region does not transport energy primarily through large-scale convection. Instead, energy moves outward mainly through radiation. Photons are repeatedly absorbed, scattered and re-emitted by particles in the extremely dense plasma. Their paths are therefore far from straight lines. A photon can change direction countless times before its energy gradually moves toward the outer layers of the Sun. The transport of energy through this region is therefore best described as radiative diffusion.

PHOTON JOURNEY

HOW ENERGY MOVES THROUGH THE RADIATIVE ZONE

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Energy generated by nuclear fusion in the core gradually diffuses outward. Photons interact with the surrounding plasma again and again, transferring energy toward the boundary with the convective zone. The animated line represents the general outward movement of energy rather than the path of one individual photon.

CORE

RADIATIVE ZONE

CONVECTIVE ZONE

PHOTOSPHERE

DID YOU KNOW?

In the radiative zone, energy can take an enormous amount of time to travel outward because photons constantly interact with the dense plasma.