The source of the sun's heat is

A. nuclear fission.

B. nuclear disintegration.

C. nuclear fusion.

D. nuclear separation.

The core of the sun is so hot and there is so much pressure, nuclear fusion takes place:hydrogen is changed to helium. Nuclear fusion creates heat and photons (light). The sun's surface is about 6,000 Kelvin, which is 10,340 degrees Fahrenheit (5,726 degrees Celsius).