Tutorial to make your own planets
Here.
As for the
_cl and
_da, not sure what they stand for, but
_cl is the light side of the planet, and
_da is the dark side of the planet.
The planet textures also have an Alpha channel, which seems to effect its reflectivity. White will reflect light, good for the oceans, ice caps, and snow capped mountains. Black is non-reflective, grass and forests etc. Grey is in between.
Planets also have a cloud layer, which is defined in their file. At the moment they all use the default 'PlanetCloudLayer'. I have made a custom one for my next mod, and after that I'm going to redo most of the cloud layers, so they are different for every planet. These have no Alpha channel, but the darker the texture, the less visible. Completely black would be clear sky, and white would be total thick cloud cover.
I'm not sure what you mean by transparency, no planet should be opaque.
