Fusion means joining smaller nuclei (the plural of nucleus) to make a larger nucleus. The sun uses nuclear fusion of hydrogen atoms into helium atoms. This gives off heat and light and other radiation.In the picture above, two types of hydrogen atoms, deuterium and tritium, combine to make a helium atom and an extra particle called a neutron.
What's better about nuclear fusion is that it creates less radioactive material than fission, and its supply of fuel can last longer than the sun.
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