There is still some uncertainty regarding the interior structure of Jupiter. One model shows a homogeneous model with no solid surface; the density may simply increase gradually toward the core. Alternatively Jupiter may possesses a dense, rocky core with a mass of up to twelve times the Earth's total mass; roughly 3% of the total mass.[21][18] The core region is surrounded by dense metallic hydrogen, which extends outward to about 78% of the radius of the planet.[18] Above lies a transparent interior atmosphere of liquid hydrogen and gaseous hydrogen, with the gaseous portion extending downward from the cloud layer to a depth of about 1,000 km.[18] There may be no clear boundary or surface between these different phases of hydrogen; the conditions blend smoothly from gas to liquid as one descends.[22][23]
The temperature and pressure inside Jupiter increase steadily toward the core. At the phase transition region where hydrogen becomes metallic, the temperature is believed to be 10,000 K and the pressure is 200 GPa. The temperature at the core boundary is estimated to be 36,000 K and the interior pressure is roughly 3,000–4,500 GPa.[18]
