What is the second atmospheric layer of the Sun, located above the photosphere?

The second atmospheric layer of the Sun, located above the photosphere, is the chromosphere.

The word chromosphere means “sphere of color,” named for the reddish glow seen around the Sun’s edge during a total solar eclipse. It lies above the photosphere and below the transition region and corona, making it the second principal layer of the solar atmosphere.

The chromosphere is normally hidden by the much brighter photosphere. Astronomers study it using specific wavelengths, especially the red H-alpha line emitted by hydrogen. Its temperature rises outward, from roughly 4,000 kelvins near the photosphere to tens of thousands of kelvins near the transition region.

A common mix-up is the corona: the corona is farther out and is the Sun’s outermost atmospheric layer. The chromosphere also contains spicules, narrow jets of plasma that can rise thousands of kilometres into the upper atmosphere.