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THE SUN  

Why We Study the Sun  
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Magnetism - The Key  

SOLAR STRUCTURE  

The Interior  
The Photosphere  
The Chromosphere  
The Transition Region  
The Corona  
The Solar Wind  
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SOLAR FEATURES  

Photospheric Features  
Chromospheric Features  
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Chromospheric Features

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The Chromospheric Network

The chromospheric network is a web-like pattern most easily seen in the emissions of the red line of hydrogen (H-alpha) and the ultraviolet line of calcium (Ca II K - from calcium atoms with one electron removed). The network outlines the supergranule cells and is due to the presence of bundles of magnetic field lines that are concentrated there by the fluid motions in the supergranules.

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Filaments and Plage

Filaments are dark, thread-like features seen in the red light of hydrogen (H-alpha). These are dense, somewhat cooler, clouds of material that are suspended above the solar surface by loops of magnetic field. Plage, the French word for beach, are bright patches surrounding sunspots that are best seen in H-alpha. Plage are also associated with concentrations of magnetic fields and form a part of the network of bright emissions that characterize the chromosphere.

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Prominences

Prominences are dense clouds of material suspended above the surface of the Sun by loops of magnetic field. Prominences and filaments are actually the same things except that prominences are seen projecting out above the limb, or edge, of the Sun. Both filaments and prominences can remain in a quiet or quiescent state for days or weeks. However, as the magnetic loops that support them slowly change, filaments and prominences can erupt and rise off of the Sun over the course of a few minutes or hours (4.0 MB MPEG movie of the "Granddaddy" prominence eruption of 1946 June 4).

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Spicules

Spicules are small, jet-like eruptions seen throughout the chromospheric network. They appear as short dark streaks in the H-alpha image to the left (National Solar Observatory/Sacramento Peak). They last but a few minutes but in the process eject material off of the surface and outward into the hot corona at speeds of 20 to 30 km/s.

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NASA Logo Image Author: Dr. David H. Hathaway, david.hathaway @ nasa.gov
Curator: Mitzi Adams, mitzi.adams @ nasa.gov

Last Updated: March 11, 2013