The examples are made using jattenalle's planets.
Even if i can't find a good alternative to povray, it is good enough, and ray tracing and how povray does textures is interesting; using cyclic parameters to stuff you can make tiling textures and stuff, and generate as many as you want by randomly translating the various patterns. You can even make different varieties of stuff, I have tried on another planet generator, but the latter is slightly more difficult. Got too many ice and desert planets, or hot planets with a lot of ocean, or stuff that didn't quite look nice. Btw, the failed attempt to add ice(caps, but also atop of mountains) here came from that.
If you know python you can script this in Blender.
I like the media(stuff that scatters, absorbs, possibly refracts) here, though, also like the isosurfaces and how 'textures' are generated. But i guess i should look at blender aswel..
Note that it isnt me not knowing python that is stopping me from using blender, it is me not finding the API conveniently enough, and lack of commandline.
Better version of the script here.