The sun radiates energy at a rate of 3.9 x 1026 W. (a) At what rate is the sun losing mass? (b) At that rate, how much time would it take to exhaust the sun’s fuel supply? The sun’s mass is 2.0 x 1030 kg, and you may assume that the reaction producing the energy is about 0.7% effi cient. Compare your answer with the sun’s expected remaining lifetime, about 5 Gy.

The sun radiates energy at a rate of 3.9 x 1026 W. (a) At what rate is the sun losing mass? (b) At that rate, how much time would it take to exhaust the sun’s fuel supply? The sun’s mass is 2.0 x 1030 kg, and you may assume that the reaction producing the energy is about 0.7% effi cient. Compare your answer with the sun’s expected remaining lifetime, about 5 Gy.