What is the main source of energy for the sun?

The main source of energy for the sun is the nuclear fusion of hydrogen into helium in its core. In the sun's core, where temperatures and pressures are incredibly high, hydrogen nuclei (protons) collide with enough force to overcome their natural repulsion due to electromagnetic forces. This collision allows them to fuse together, resulting in the formation of helium nuclei.

During this fusion process, a tiny amount of mass is converted into energy according to Einstein's famous equation, E=mc². This energy is released in the form of light and heat, which ultimately powers the sun and provides energy to the entire solar system. This process is highly efficient and capable of producing immense amounts of energy that sustain the sun for billions of years.

The other options, while related to potential sources of energy, do not accurately describe the primary mechanism powering the sun. For instance, fission involves splitting heavy nuclei rather than fusing light ones, which does not occur in the sun. Gravitational collapse may contribute to the initial formation of the sun, but it is not the ongoing source of energy. Lastly, chemical reactions generate much less energy compared to nuclear processes and are not responsible for the sun's output. Thus, nuclear fusion of hydrogen into helium is the