Newest addition:
Planet 4 constructed from the textures for planet Mercury, and the moons Dione and Enceladus.
I have a star system artwork project going, so this is planet 4. Planet 1 is the red hot one on the first page. Planet 2 is the second hot (but not glowing hot) planet on the first page, but I decided to have it tidally locked so now it looks like this:
Planet 2
Same with planet 3 which is now also tidally locked:
Planet 3
Getting planets tidally locked in celestia was difficult. I had to consult someone on the celestia forums to figure out how to code it.
The next one I'm working on isn't a barren planet like the previous ones, but one with liquid water on its surface.