An ETI species is given a boost into a Scientific-Industrial Revolution by their observations of a supernova. Just as they approach starflight capability they discover that their own star is about to do the same thing. They just manage to get one off in time (and when the SN occurs they are fighting a war between the two Poles). The ship goes to various supergiant stars looking for habitable planets, but each planet they try has something wrong with it. After a long while, they decide to try a yellow dwarf (which won't go supernova on them) even though there are fewer planets in the habitable zones of such stars. The first one they try is a habitable one (it is implied that it is Sol and they are our ancestors).