Fusion is the process that powers stars. This is where lighter atomic nuclei, like hydrogen, combine to form heavier nuclei, like helium, releasing tremendous amounts of energy. This is what makes stars shine.

Fission is the process where a heavy atomic nucleus, like uranium, is split into lighter nuclei, also releasing energy. This is the process used in nuclear power plants.

Here's why fission doesn't happen in stars:

* Temperature and Pressure: The conditions inside stars are too hot and dense for fission to occur. The high temperatures would cause the fission products to fly apart before they could be captured.

* Nuclear Fuel: Stars are primarily made of hydrogen and helium, which are the lightest elements. Fission requires heavier elements like uranium or plutonium.

To summarize: Stars are powered by fusion, not fission.