Q:  The solar luminosity is about L = 3.8 x 10^(26) J/s.
         How long would it take the Sun to generate enough energy
         to blow itself apart?


                     2.3 x 10^(41) J
          time  =  -------------------   =   6 x 10^(14) s
                     3.8 x 10^(26) J/s


                =  about 19 million years