The solar core is the hot, dense region at the center of the Sun where energy is generated by nuclear fusion. It is considered to extend from the Sun's center to about 0.2 of the solar radius. It is the hottest part of the Sun and of the Solar System. It has a density of 150,000 kg/m3 (150 g/cm3) at the center, and a temperature of 15,000,000 K.