[填空题]
The Sun radiates energy at 9xs y )nb13lkqs-,z jbx vwu.k; f(zc:b/ r zud3h36uqa rate of about $4 \times 10^{26} \, \text{W}$.
(a) At what rate is the Sun's mass decreasing?$\frac{\Delta m}{\Delta t}$ = $ \times 10^9 \, \text{kg/s}$
(b) How long does it take for the Sun to lose a mass equal to that of Earth?$\Delta t$ = $ \times 10^{15} \, \text{s}$
(c) Estimate how long the Sun could last if it radiated constantly at this rate.$\Delta t$ = $ \times 10^9 \, \text{yr}$
