Original: Saturn has a very hot interior, reaching 11,700 °C at the core, and it radiates 2.5 times more energy into space than it receives from the Sun.
Simplified: It has a small rocky core at its centre and it is very hot; its temperature reaches 15,000 K (26,540 °F, 14,730 °C). It is so hot that it radiates about two and a half times more heat energy into space than the amount of energy Saturn receives from the Sun.