How does nuclear fusion power stars?

Nuclear fusion powers stars by converting hydrogen into helium through a process of fusion reactions.

Nuclear fusion is the process by which atomic nuclei combine to form heavier elements. In stars, the process begins with the fusion of hydrogen atoms to form helium. This process releases a tremendous amount of energy in the form of light and heat. The energy generated by nuclear fusion is what powers the sun and other stars.

The process of nuclear fusion occurs at extremely high temperatures and pressures. In the core of the sun, temperatures reach over 15 million degrees Celsius, and pressures are over 250 billion times that of Earth's atmosphere. At these extreme conditions, hydrogen atoms are able to overcome their natural repulsion and merge together to form helium.

The fusion process releases energy in the form of photons, which are absorbed and re-emitted by the surrounding matter. This energy eventually makes its way to the surface of the star, where it is radiated out into space as light and heat.

The process of nuclear fusion is incredibly efficient, with nearly all of the mass of the hydrogen atoms being converted into energy. This is what makes nuclear fusion such an attractive source of energy for human use. However, reproducing the conditions necessary for nuclear fusion on Earth remains a significant technical challenge.