Internal Compression

Internal Compression

. The Sunís luminosity, temperature, and composition all vary with depth in its interior, from the Sunís visible disk (left) to the center of the Sun (right). The nuclei are squeezed into a smaller volume by the pressure of the material above, becoming hotter and more densely concentrated at greater depths. At the Sunís center, the temperature has reached 15.6 million degrees Kelvin, and the pressure is 233 billion times that of the Earthís atmosphere at sea level. Nuclear fusion reactions in the Sunís energy-generating core synthesize helium from hydrogen, so this region contains more helium and less hydrogen than the primordial amounts detected in the light of the visible Sun.

Copyright 2010, Professor Kenneth R. Lang, Tufts University