The colony ship is kit bashed from various 3d parts.
This means I can quickly iterate on the design in CryENGINE. Everything is simply linked to a tagpoint (null entity). Including parts I can detach and animate separately.
For the Earth I use a few different texture maps including separate maps for the clouds, and glowing city lights.
The Earth is a giant sphere in Cryengine.
The sun is simply a sphere with glow material, with a light with flare rendered over the top.
Everything is rendered in CryENGINE and running in real-time.