The chromosphere is the layer of the Sun's atmosphere that lies above the photosphere and below the corona. It is about 10,000 kilometres thick, and has a temperature of about 10,000 degrees Celsius. The chromosphere is responsible for the Sun's red colour.

The chromosphere is a region of the Sun where many different types of activity occur, including:

* Spicules: These are jets of hot gas that erupt from the photosphere into the chromosphere. They are typically only a few hundred kilometres wide, and last for a few minutes.

* Prominences: These are large, glowing clouds of gas that extend from the chromosphere into the corona. They can be hundreds of thousands of kilometres wide, and last for several weeks.

* Flares: These are sudden, intense bursts of energy that occur in the chromosphere. They can last for several minutes, and can release an enormous amount of radiation.

The chromosphere is a dynamic and active region of the Sun, and is a key component of the Sun's atmosphere.