Final answer:
The Sun generates energy through the process of nuclear fusion, where hydrogen nuclei combine to form helium, releasing vast amounts of energy.
Step-by-step explanation:
The process which generates energy in the Sun is nuclear fusion. This process occurs when very light nuclei, such as hydrogen, combine to form heavier nuclei, like helium. The Sun's principal energy-producing sequence is the proton-proton cycle, where four hydrogen nuclei (1H) fuse together to produce one helium nucleus (4He) along with two positrons and gamma rays. As the hydrogen nuclei fuse, mass is converted into a tremendous amount of energy, which is the source of the Sun's radiance and warmth. This differs from nuclear fission, which involves the breaking apart of heavier atomic nuclei into lighter ones, and is utilized in nuclear reactors and atomic bombs here on Earth.