When the Sun becomes a red giant star, what will happen to the outer planets and their satellites?


They will get a lot warmer. The mostly icy moons of Jupiter and Saturn will probably develop liquid oceans and thick atmospheres rich in water vapor, and photoionized water and methane ammonia gases. The problem is that the red giant phase lasts only a few hundred million years so that any living systems that survive on these distant satellites have only a short life span before the Sun becomes a cool white dwarf and freezes the surfaces of these satellites back to ice.