Very great tool, planet looks very cute and ready to be used in any sci-fi game (cut scene, intro/outro, background, scenery), I can't even believe what I see as being randomly generated ! Great job and congratulations on keep the will to continue improving it over and over.
There is still work to do on asteroids which looks mostly odd for now.
I've started years ago to create such tool for one of my project, didn't go too far and I got something like this:
with using only blue color for this sample (Perlin noise), with MonoGame in C#. I've plan to add atmosphere but never did it.