I’m imagining at least one rogue planet out there (they said they could be billions) was happily orbiting a star for billions of years, life formed, even relatively intelligent life, and then another rogue planet fell in to the solar system and passed right by the first planet in such a way as to eject it from the solar system without hitting it, and all this life on the planet suddenly loses daylight as their planet flies off in to deep space. And now their ancient civilization is frozen in time, adrift in deep space.