Good news Pure-Sky 2.2 is out and now you can display a moon and a planet. In this version the celestial bodies have all been completely recreated for an even more realistic rendering.
Pure-Sky allows you to cycle days and nights automatically with a realistic or cartoon style.
Pure-Sky automatically generates realistic lighting by projecting adaptive light and soft or hard shadows depending on the time of day. Pure-Sky is the first and only procedural sky for Blender that directly includes real-time lens flares and lens dirt with obstacle detection.