Object: The Sun Rotation: 25 days Mass: 333,000x of Earth Temp: 15,000,000 C in core, 5500 C at surface General Description: The Sun is the only star in the solar system. A yellow dwarf, it is the prime of its life. It burns hydrogen into helium at its core by the process of thermonuclear fusion. Temperatures caused by this fusion can run as high as 15 to 20 million degrees. The surface temperature is cooler at a mere 6 thousand degrees.