Chromosphere — The chromosphere (literally, “color sphere”) is a thin layer of the Sun’s atmosphere just above the photosphere, roughly 10,000 kilometers deep. The chromosphere is more visually transparent than the photosphere.
The most common solar feature within the chromosphere are spicules, long thin fingers of luminous gas which appear like the blades of a huge field of fiery grass growing upwards from the photosphere below. Spicules rise to the top of the chromosphere and then sink back down again over the course of about 10 minutes.
Another feature found in the chromosphere are fibrils, horizontal wisps of gas similar in extent to spicules but with about twice the duration.
Finally, solar prominences rise up through the chromosphere from the photosphere, sometimes reaching altitudes of 150,000 kilometers. These gigantic plumes of gas are the most spectacular of solar phenomena, aside from the less frequent solar flares.