Science
How does nuclear fusion work?
Nuclear fusion works by forcing light atomic nuclei — like hydrogen — together under extreme heat and pressure until they merge into a heavier nucleus, releasing enormous energy. It powers the Sun and stars, and scientists are working to harness it on Earth.
See it in motion.
Watch a 2-minute animated lesson that shows exactly how nuclear fusion works.
Step by step
- 1Light nuclei are fused into a heavier one.
- 2It requires extreme heat and pressure.
- 3It releases vast energy — more than fission.
- 4It powers the Sun and stars.
Frequently asked questions
- How does nuclear fusion work?
- Extreme heat and pressure force light nuclei to merge into a heavier one, releasing huge amounts of energy.
- What's the difference between fusion and fission?
- Fusion joins light atoms together; fission splits heavy atoms apart.
- Why don't we use fusion for power yet?
- Sustaining the extreme conditions and getting more energy out than in remains a major engineering challenge.