Nuclear Reactions

The sun generates its energy by breaking and reconnecting the bonds between particles inside the atomic nuclei. Particles, being: protons and neutrons, located in the nuclei of atoms.













Nuclear Fission reactions split the large nuclei to smaller nuclei, releasing energy. An example above would be ²³⁵Uranium splitting to fragments with mass number around 118.

Nuclear Fusion reactions combine light nuclei into heavier nuclei to release energy. Since protons have like charges, they don't want to combine! However, in the center of the Sun, densities are extremely high and the particles hit each other with such high speeds (due to their hot temperature), as to overcome this Coulomb Barrier.

Nuclear Fusion Reactions only occur at the center of Stars

Iron has the most tightly bound nucleus. You can not generate ANY energy once you arrive at Iron, via fusion or fission.