Q:  The Sun's luminosity is  L = 4 x 10^(26)  Joules/sec.
         How long would the Sun have to shine to release as much energy
         as a supernova explosion?


           A typical supernova explosion releases around 10^(44) Joules
             over the course of several weeks or months.

                            10^(44) Joules
              time  =  --------------------------   =   2.5 x 10^(17) sec
                         4 x 10^(26) Joules/sec


                           2.5 x 10^(17) sec
                    =    -------------------------  =     8 billion years
                           3.15 x 10^(7) sec/year


           It takes the Sun a long, long time to release this much energy!