What powers the Stars?

Stars are powered by nuclear fusion, a process that occurs in their cores where extreme temperatures and pressures enable hydrogen atoms to fuse into helium. This fusion releases vast amounts of energy in the form of light and heat, which is what we observe as starlight. As stars evolve, they can fuse heavier elements, sustaining their energy output throughout different stages of their life cycles. Ultimately, the balance between gravitational forces and the energy produced by fusion determines a star's stability and lifespan.