What is the source of energy of sun or stars ?

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: We need to determine the source of energy for the Sun and other stars.

2. **Identifying the Main Process**: The primary source of energy in the Sun and most stars is a nuclear reaction known as nuclear fusion.

3. **Explaining Nuclear Fusion**: In the Sun, hydrogen atoms undergo fusion to form helium atoms. This process releases a significant amount of energy.

4. **Energy Release**: The energy released from this fusion reaction is what we perceive as sunlight and is responsible for the warmth and light that the Sun provides to Earth.

5. **Other Sources in Stars**: While nuclear fusion is the main source of energy in the Sun and many stars, some stars utilize a different process known as the carbon cycle for energy production.

6. **Conclusion**: Therefore, the energy of the Sun and most stars primarily comes from nuclear fusion, with some stars also using the carbon cycle.

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