Open Site - Science: Astronomy: Solar System: Sun: Interior

Top: Science: Astronomy: Solar System: Sun: Interior

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Overview

To understand how our Sun works, it helps to imagine that the interior of the Sun is made up of different layers, one inside the other. The innermost layer, the solar core, is the region where the energy of the Sun is produced. This energy travels through the next layer of the solar interior, called the radiation zone, and eventually reaches the convection zone, where energy is transferred mainly by the overturning of solar gases. This convection produces an everchanging pattern of cells on the surface of the sun.

Direct observations inside the Sun are not possible, however some diagnostics exist that allow us to study the Sun's interior.

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Convection Zone

The convection zone in the Sun occurs above the radiative zone, at about .7 to .8 solar radii from the center of the Sun. At this point the temperature gradient (the change in temperature with depth) becomes so large that turbulent convective motions occur, similar to a pot of boiling water. The overturning motions inside the Sun are responsible for the granulation pattern seen on the Sun's surface.

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Solar Core

The solar core is made up of an extremely hot and dense gas (in the plasma state). Despite a density of 160,000 Kg/m3, the temperature of 15 million degrees Kelvin (27 million degrees Faranheit) prevents the core from reaching the solid state.

The core is the region where the energy of the Sun is produced. The density and temperature are such that nuclear fusion reactions can take place: these reactions release energy both in the form of electromagnetic energy (gamma rays) and particles (in particular neutrinos). Despite the reactions, the Sun's core is a very dark place!