CHROMOSPHERE

n. outer layer of the sun's atmosphere (Astronomy)

The chromosphere (literally, "color sphere") is a thin layer of the Sun's atmosphere just above the photosphere, roughly 10,000 kilometers deep (approximating to, if a little less than, the diameter of the Earth). The chromosphere is more visually transparent than the photosphere. The name comes from the fact that it has a reddish color, as the visual spectrum of the chromosphere is dominated by the deep red H-alpha spectral line of hydrogen. The coloration may be seen directly with the naked eye only during a total solar eclipse, where the chromosphere is briefly visible as a flash of color just as the visible edge of the photosphere disappears behind the Moon.
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Noun
1. a gaseous layer of the sun's atmosphere (extending from the photosphere to the corona) that is visible during a total eclipse of the sun
(hypernym) layer
(part-holonym) sun

n. chromosphere

(n.)
An atmosphere of rare matter, composed principally of incandescent hydrogen gas, surrounding the sun and enveloping the photosphere. Portions of the chromosphere are here and there thrown up into enormous tongues of flame.