1.5 x 10^(11) m
   t(A)   =  ----------------------   =  500.3 seconds
               299,792,458 m/s


                1.5 x 10^(11) m
   t(B)   =  ----------------------   =  500.3 seconds
               299,792,458 m/s


Each photon takes the same time to reach the Earth:

     t(A) - t(B) = 0