The Sun's atmosphere is mainly two layers namely, The Chromosphere and The Corona.
- In above figure, we can see Chromosphere lies above the Photosphere and extended upto~2000km.
- Chromosphere is about 5 times as denser as earth's atmosphere.
- The density of the chromosphere is only 10−4 times that of the photosphere, the layer beneath, and 10−8 times that of the atmosphere of earth at sea level.
- This layers is normally not visible from earth because of its faintness. it can be seen during a solar eclipse.
- In the chromosphere, the density decreases by a factor of ~ 10000 km from that of the photosphere while the temperature rises to ~ 25000 K within a short distance of ~ 2000 km.
- The density of the chromosphere decreases with distance from the center of the Sun.
- Chromospheres have been observed also in stars other than the Sun.
Q. Why does the temperature in the chromosphere increase with height?
The clue to the answer of this question lies in observing the chromosphere just before the total solar eclipse. Hot gas, in the form of jets called spicules, is observed throughout the chromosphere (Fig. below). These spicules extend upward in the chromosphere up to a height of ~ 10000 km and last for as long as 15 minutes. This implies that the lower part of the chromosphere is highly turbulent and the spicules transport energy and matter from the photosphere to the chromosphere. This causes heating of the chromosphere.
