Which process powers stars by combining light nuclei?

Which process powers stars by combining light nuclei?

• A. Nuclear fission
• B. Nuclear decay
• C. Ionization
• D. Nuclear fusion

Answer: (D)

Stars get their energy from fusing light nuclei into heavier ones. In the hot, dense cores, nuclei such as hydrogen collide and fuse to form helium, and this fusion releases energy because the resulting nucleus is more tightly bound. The mass difference shows up as energy (E = mc^2), which makes its way outward as heat and light that power the star. The dominant path in many stars is the proton–proton chain, which gradually converts hydrogen to helium and radiates energy along the way. Nuclear fission splits heavy nuclei into lighter ones and isn’t how stars generate their energy. Ionization is just removing electrons and doesn’t release the large, sustained energy that fuels stars. Nuclear decay also releases energy but occurs spontaneously and doesn’t provide the steady fusion energy that sustains stellar luminosity.

Stars get their energy from fusing light nuclei into heavier ones. In the hot, dense cores, nuclei such as hydrogen collide and fuse to form helium, and this fusion releases energy because the resulting nucleus is more tightly bound. The mass difference shows up as energy (E = mc^2), which makes its way outward as heat and light that power the star. The dominant path in many stars is the proton–proton chain, which gradually converts hydrogen to helium and radiates energy along the way. Nuclear fission splits heavy nuclei into lighter ones and isn’t how stars generate their energy. Ionization is just removing electrons and doesn’t release the large, sustained energy that fuels stars. Nuclear decay also releases energy but occurs spontaneously and doesn’t provide the steady fusion energy that sustains stellar luminosity.