I think i can safely say that now, everything is close to what i envisionned. In disorder, i fixed the sun color at right angles, the contrasts of the starfield, the quality of the cloud textures and adjusted some parameters. The first screen is an Earth-like planet with an atmosphere thickness of 250 kilometers (gives an "artistic" feeling to it), the second one has a thickness of 100 kilometers, which is more realistic, but looks less nice in my opinion.
Reducing the images to fit in this journal makes them a bit blurry. For fun, i upped the resolution to 1600x1200 with antialiasing x6, planet textures 1024x1024 and took a screenshot (maybe if some of you need a new wallpaper). It still rendered at more than 60 fps on my machine.Link to wallpaper-ed image (500 Kb)
I can finally move on to other tasks. I need to work on my 4E4 entry, too..