Generation of solar spicules and subsequent atmospheric heating

The temperature drops from^16 million Kelvin at the core of the Sun to 5700 K at the solar surface(photosphere).However,the temperature increases with height above the photosphere,reaching one million degrees or more in the solar corona.Due to this high temperature,the corona naturally expands to the interplanetary space,forming the solar wind.What causes the temperature increase in the corona is one of the biggest mysteries in astronomy.