Final answer:
The Sun loses energy by converting mass into energy through nuclear fusion, losing about 4 × 10⁹ kg of mass every second. This equates to a power output of approximately 3.8 × 10²⁶ J/s. Although the mass lost per second is significant, it is minor compared to the Sun's total mass, enabling it to shine for billions of years.
Step-by-step explanation:
The Sun loses energy primarily by converting mass into energy through the process of nuclear fusion. This fusion occurs in the Sun's core, where hydrogen nuclei combine to form helium, in a reaction expressed by Einstein's mass-energy equivalence formula, E=mc². Using this formula, it can be calculated that the Sun loses about 4 × 10⁹ kg of mass every second.
This massive energy production equates to a power output of approximately 3.8 × 10²⁶ joules per second (J/s). The fusion process is incredibly efficient, but since the Sun is composed mostly of hydrogen and is so massive, it can continue to produce energy at this rate for billions of years without running out of fuel. The loss of mass is negligible compared to the total mass of the Sun, but over astronomical timescales, it will result in a significant decrease in the Sun's mass.