Every year in the galaxy, more than 2,000 suns enter late-phase in their fusion-burning cycles, expanding their surfaces and becoming much hotter than before. Another twenty stars per year go nova… .
Taking into account the millions of stars that have habitable planets, this means that on average two human-settled worlds become untenable or uninhabitable each year…Throughout the early dark ages, before the Galactic Empire, numerous tragic natural disasters cost billions of lives. Isolated worlds often had nowhere to turn for help when a sun went unstable, or something disrupted a planetary ecosphere.
During the Imperium such threats were handled on a routine basis by the Grey bureaucracy, which efficiently surveyed stellar conditions, predicted solar changes in advance, and maintained resettlement fleets on standby to deal with emergencies. So dedicated was this effort that remnants still existed late in the empire’s decline, arriving to help evacuate Trantor when the capital planet was sacked.
Thereafter, during the Interregnum, such assistance was unavailable. Scattered accounts tell of numerous small worlds that went abruptly silent during that long, violent era, owing to natural or man-made calamities. Often no one bothered to go learn what happened to their populations until it was too late…
Even after the rise of the Foundation, it took some time before a combination of psychohistorical factors made possible the investment of substantial resources to build an infrastructure of compassion… .