Chromosphere

2,500 km thick (1,600 mi) layer of plasma above the Sun’s photosphere. Temperatures range from ~4500 K to 60,000 K (110,000 to 8,000°F). The word chromosphere means, literally, “color sphere” and refers to its reddish color when seen with the naked eye during a total solar eclipse.

The irregular layer of the solar atmosphere that is located above the photosphere and beneath the corona. The temperature in the chromosphere rises from 6000° C to about 20,000° C. It is hotter than the photosphere but not as hot as the corona. At these higher temperatures hydrogen emits light that gives off a reddish color (called H-alpha emission). This colorful emission can be seen in prominences that project above the surface of the Sun during total solar eclipses. This is what gives the chromosphere its name (color-sphere). The chromosphere also produces most of the UV light from the Sun.

In solar-terrestrial terms, the layer of the solar atmosphere above the photosphere and beneath the transition region and the corona.