Which one happens in the Sun, Fission or Fusion?

Question

and which one needs greater amount of energy?

Answer 1

Fusion of hydrogen into helium

For  starting a fusion reaction temperature of millions of degree required  then it will release energy as per Einsteins equation.

Answer 2

Fusion is in the sun. It needs a greater amount of energy to get started, but then it releases a whole bunch of energy.

Fusion is the combination of atoms in to heavier atoms. The smallest form of it is hydrogen into helium but you can get bigger atoms with it. The largest atom you can produce and still get a net gain of energy is iron.

Answer 3

Fusion, I believe it creates more energy than it uses.

Answer 4

Fusion.

Essentially, hydrogen is fused into helium.

More matter is being converted to energy in this process than in a fission reaction - hense more energy is released.

Remember, E=MC2.