The chromosphere (literally, "color sphere")'s a thin layer of the Sun's atmosphere just above the photosphere, roughly 2,000 kilometers deep. The chromosphere's more visually transparent than the photosphere. The name comes from the fact that it's a reddish color, as the visual spectrum of the chromosphere's 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's briefly visi… (More on Chromosphere)