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THE SUN  

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SOLAR STRUCTURE  

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The Chromosphere

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The chromosphere is an irregular layer above the photosphere where the temperature rises from 6000°C to about 20,000°C. At these higher temperatures hydrogen emits light that gives off a reddish color (H-alpha emission). This colorful emission can be seen in prominences that project above the limb of the sun during total solar eclipses. This is what gives the chromosphere its name (color-sphere).

 

 

When the Sun is viewed through a spectrograph or a filter that isolates the H-alpha emission, a wealth of new features can be seen. These features include the chromospheric network of magnetic field elements, bright plage around sunspots, dark filaments across the disk and prominences above the limb.

The chromosphere is the site of activity as well. Changes in solar flares, prominence and filament eruptions, and the flow of material in post-flare loops can all be observed over the course of just a few minutes.

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The chromosphere is also visible in the light emitted by ionized calcium, Ca II, in the violet part of the solar spectrum at a wavelength of 393.4 nanometers (the Calcium K-line). This emission is seen in other solar-type stars where it provides important information about the chromospheres and activity cycles in those stars.

 

 

Solar Chromosphere Web Links

Latest H-alpha images - Current (up to the minute) images of the sun in H-alpha

Latest images - BBSO Latest images of the chromosphere in H-alpha

Web Links
NOAA's Space Weather Prediction Center - Today's Space Weather Updated Every 5-minutes
sdo.gsfc.nasa.gov/data/ - Latest Images from the Solar Dynamics Observatory
National Space Weather Program - The U.S. Government and Space Weather
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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: August 11, 2014