Activity in the Chromosphere and Corona
Extending out from the photosphere is the Sun’s atmosphere. It can be divided into two main regions – the chromosphere and the corona. The chromosphere is a layer of tenuous gas with a density much less than that of the photosphere. It is about 2,500 km thick with a temperature that varies from 6,000°C just above the photosphere to about 20,000–30,000°C at its top. The chromosphere is characterised by spikes of gas called spicules, giant flames called prominences and solar flares. The chromosphere is important to scientists because it is largely responsible for the deep ultraviolet radiation that bathes the Earth, producing our atmosphere’s ozone layer, and it has the strongest solar connection to climate variability.