Problem
A solar system is a good first real scene: enough moving parts (8 planets, their moons, a sun) to force real decisions about scale, lighting, and camera control, without needing gameplay logic on top.
Approach
A camera fly-in intro leads into a draggable orbit around the sun. Saturn gets rings, several planets get cloud layers, and the background is an 8K starfield rather than a flat black—small details, but they're the difference between a demo and something that looks finished.
What I'd change
Orbital periods and sizes are visually plausible, not physically scaled—a real-scale model would either put Pluto off-screen or shrink the sun to a dot. Worth a toggle between "looks good" and "actually to scale" rather than picking one.