The chromosphere is a layer of the Sun's atmosphere located above the photosphere and below the corona. It is about 2,000 to 3,000 kilometers thick and is primarily composed of hydrogen and helium. The chromosphere is visible during a total solar eclipse as a reddish glow, which is caused by the emission of light from hydrogen atoms. This layer plays a crucial role in solar activity, including the formation of solar prominences and solar flares. The temperature in the chromosphere increases with altitude, reaching up to 20,000 degrees Celsius. Studying the chromosphere helps scientists understand the dynamics of the Sun and its impact on the solar system.