Energy can be liberated from atomic nuclei in several ways via nuclear fission, or nuclear fusion.
In fission, heavy nuclei are broken apart to create smaller nuclei, releasing energy in the form of photons.
The problem with fission is that often the lighter products of the process are ‘radioactive isotopes’. These are unstable nuclei that spontaneously decay into other elements by releasing electrons, positrons, helium nuclei, or very energetic gamma-ray photons. These particles, often called ‘radiation’, are hazardous to life.
In fusion, lightweight atomic nuclei liberate energy when they combine to form heavier elements. Deep in the Sun’s core, at high temperatures and pressures, hydrogen nuclei are fused to make helium nuclei. This releases large amounts of energy in the form of neutrinos and gamma-ray photons, as well as the kinetic energy of the helium nuclei.
Each high-energy gamma-ray produced in the Sun’s core, on its long journey to the solar surface, is converted into millions of visible light photons. That is the source of the ‘radiation’ we receive from the Sun. So, the Sun produces dangerous radiation, but only electromagnetic radiation — and none of the nasty radioactive by-products associated with fission reactions.
Fusion reactions produce, pound for pound, more energy than fission reactions. However, fusion reactions require extremely high temperatures and pressures to get started. This is why we have notyet fully solved the production of clean and efficient fusion energy.
Read more:
- Why do both fission and fusion release energy?
- If the Sun is constantly losing mass via nuclear fusion, how come it’s not getting any smaller?
- Who really discovered nuclear fission?
Asked by: Hurley, via email
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