So I started reading a novel somewhere around 20 years ago and I'm very fuzzy on the details. What I remember is it involved a cloud of darkness just kind of rolling over and consuming everything it happened to touch. It was quite creepy and my then 12(ish) year old self wasn't capable of appreciating nightmare fuel and abandoned ship. (Did the same thing with the first of Alten's Meg books...)
I'm fairly certain I'm -not- thinking of Asimov's Nightfall... That seems far less... creepifying than I remember. Also if memory serves (sometimes it doesn't) it was set on Earth; and I'm pretty sure a detail like six suns would habe stood out. The part that -is- still etched into my memory is a scene where this dark cloud of maybe aliens consumes a small farmhouse.