The Sun

The Sun consists of two regions, the interior and outer atmosphere. The interior is made up of three layers:

The Core

The core is where 99% of the energy is generated by nuclear reactions. The energy is released in the form of high energy photons.

The Radiative Zone

The next layer is the radiative zone, where the energy from the core travels outwards by the process of radiation in the form of high energy photons. The photons are absorbed and reemitted many times. The interior is so optically thick that even though a photon could travel a solar radius in two seconds, it takes 10 million years for a photon from the core to leave the sun.

The Convection Zone

The convection zone is relatively thin compared to the radiative zone and the high temperature difference across it causes convective flow of plasma. The convection of charged particles causes magnetic fields, which in turn interact with the convection and which also can cause magnetic disturbances in the next solar layer, the photosphere. This convection is the key to understanding sunspots.

The Photosphere

The photosphere is much thinner than the convection layer, and is the part of the sun which we see as the bright outer layer. It derives its name from the Greek word for light. This is where sunspots are manifested.

The Chromosphere

The chromosphere is usually visible during solar eclipses as a colorful halo outside of the photosphere, and is named after the Greek word for color. It is very thin, and usually only diffuses light radiated by the Photosphere.

The Corona

The corona is thinner than the chromosphere and extends far beyond the orbit of earth, consisting of matter which is emitted by the sun in the form of the solar winds.

Eigenfunction Analysis of Coherent Structures on the Solar Surface
Authoring NASA Official:Dr. Milton Halem, Chief, Earth and Space Data Computing Division
Contact:Marilyn Mack/Code 930 marilyn.j.mack.1@gsfc.nasa.gov