Which process powers the Sun by converting hydrogen into helium?

• A. Gravitational contraction
• B. Solar wind heating
• C. Nuclear fusion of hydrogen into helium
• D. Chemical burning of hydrogen

Answer: (C)

Nuclear fusion in the Sun’s core powers it by fusing hydrogen into helium. In the extreme heat and pressure there, hydrogen nuclei collide and fuse to form helium, releasing vast amounts of energy that escape as sunlight. This ongoing fusion is what sustains the Sun’s light and warmth over billions of years. Gravitational contraction played a crucial role in the Sun’s formation, but it does not supply the Sun’s current steady energy output. Solar wind heating arises from charged particles and magnetic activity, not from hydrogen turning into helium. Chemical burning would require chemical reactions at much lower temperatures and energies, which does not occur in the Sun’s hot, ionized interior. So, nuclear fusion of hydrogen into helium best explains the Sun’s power.