# Nuclear Fusion

Nuclear fusion involves two atomic nuclei joining to make a large nucleus. Energy is released when this happens.

The Sun and other stars use nuclear fusion to release energy. The sequence of nuclear fusion reactions in a star is complex, but overall hydrogen nuclei join to form helium nuclei. Here is one nuclear fusion reaction that takes place:

hydrogen-1 nuclei fuse with hydrogen-2 nuclei to make helium-3 nuclei

$_{1}^{1}\textrm{H}+_{1}^{2}\textrm{H}\rightarrow _{2}^{3}\textrm{He}$