Sun: 3D Cutaway Model
The Sun’s visible surface, called the photosphere, radiates at about 5,500 degrees Celsius. Below it lies a turbulent region that extends a third of the way down, where the temperature reaches two million degrees. This outer region contains two-thirds of the Sun’s volume, but only 5 percent of its mass. Most of the Sun’s mass lies in a stable underlying zone, where temperatures rise to 10 million degrees. In the core of the Sun, where nuclear fusion occurs, temperatures reach 17 million degrees. The core contains one-third of the Sun’s mass, packed into 1 percent of its volume.