What is the process by which two light atomic nuclei combine to form a heavier nucleus?

Explanation

Nuclear fusion occurs when two light nuclei smash together with enough energy to combine into a heavier nucleus. This process releases enormous amounts of energy.

The sun and stars produce energy through fusion, combining hydrogen nuclei to form helium. Fusion requires extremely high temperatures and pressures to overcome the repulsion between positive nuclei.

Fusion is the opposite of fission, which splits heavy nuclei apart. Scientists are working to harness fusion as a clean energy source on Earth.