Q:  How long does it take a neutrino to travel from the core of
           the Sun to the Earth?


         Distance from Sun to Earth      D   =  1 AU  =  1.5 x 10^(11)  m

         speed of neutrino  (approx)     v   =   c    =  3.0 x 10^(8) m/s


         So the time to make the trip is


                     1.5 x 10^(11) m
               t  =  ----------------  =  500 seconds  =  8.3 minutes
                      3 x 10^(8) m/s




  Q:  How quickly will neutrino telescopes notice that something
           has changed?


          In just over 8 minutes, neutrino telescopes could detect
             that the flux of neutrinos from the Sun has disappeared.
             
          In practical terms, given the relatively low efficiency of
             these detectors and the time required for analysis, 
             people might start to spread the word in an hour or two.