There's a thing in science fiction called the Big Dumb Object which always provokes awe and a sense of wonder and all that, and Eon is all about one of those. They're called big dumb objects because boys of all ages love them, their eyes go all glazey thinking about the size, power and size of these things and all the author has to do is make sure their alien object is really really big. Works every time. Boys love size - breasts, penises, brothers, breakfasts, all good as long as they're big. So, for instance, Rama in Arthur Clarke's Rama books is one, the Ringworld in Ringworld by Larry Niven is another, the house in House of Leaves is one, apparently there's a giant black hole known as the Unicron singularity in Transformers: Cybertron so that's another, and it goes on and on. Every invasion of earth has a big dumb object in the sky called a spaceship. 
 So in Eon you get a big asteroid thing hanging up there in the sky which when they go and investigate they find it's bigger inside than it is outside. 
 Ooooh. 
 Probably things that are bigger inside than they are outside are just metaphors for the human brain. 
 So it's the house in House of Leaves (which was the same house that was in House, an old horror movie from 1986) only it's in the sky with scientists. And plus, when the scientists go and explore it, or the guy in House of Leaves rides off on his bike to investigate the vastness of the House, it's like when kids in stories find doors in trees or in the back of wardrobes and they get to explore a magical kingdom. That part of it is probably all to do with sex, when you think about it. 
 Eeek. 
 I was a boy once and have never lost my liking for big dumb objects and secret doors and the frissons they can evoke.