Cheers, folks!
Harvey Birdman: No, there is only one lightsource, our normal sun, there are several different luminosity functions in play though throughout the render, including the starchart image map on the floor, the starfields on either wall and, the 'sand' on the little planet is just a luminosity function applied to the main rock surface of the ground, via an image mask drawn around the waterline of the planet.
There is also some luminosity in the Moon and the 1950's 'rays' from the telecomm's tower.
The ocean is a sphere set just smaller than the planet, the main displacement on the surface creates the ocean 'troughs', this is obviously planetary water coverage as opposed to strategicaly placed circular lake objects, works on large scale too.
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Balls of hollow cloud can be rendered this way, something I realised a while ago and haven't posted anywhere...
Create a new planet >> add a cloud layer to it's atmosphere >> uncheck 'render surface' on the new planet's settings. Now you'll render a ball of complete atmosphere, check/uncheck the primary/secondary levels to suit what you need. Could be good for simulating duo-layered clouds, with one cloud layer, if the outer edge of the sphere is outside the camera's FOV... I might play with this idea.