Atomic Physics C. Nuclear Fusion Key Concepts Nuclear fusion occurs when two small nuclei join together to form a larger nucleus. A large amount of energy is released during fusion.
Nuclear fusion occurs within the sun and the stars.
Fusion in the sun is believed to occur in steps. Four protons produce one atom, two positrons, and two neutrinos. Sunlight is energy released from fusion reactions in the sun. Examining the spectral characteristics of stars may provide a better understanding of fusion. Fusion is believed to be possible only under extremely high temperatures.