So, "The Vela", a collaborative science fiction novel written in relatively self-contained chapters by @slhuang, @deuceofgears, Becky Chambers, and Rivers Solomon.
Set in a solar system with many inhabited planets, each with its on distinct politics and culture - without them being monocultures.
But there's a problem here: the sun is slowly going out, because some inner planets overdid the Hydrogen harvesting. This renders the planets uninhabitable one by one.
(1/n)