Flattering, but I'm undeserving of all the credit. While I am a Landscape Architect by profession and a Map-Making Gamer at heart, I'm merely a messenger in this case. All images used were found by a simple Google image search. All had to be modified and enhanced or cleaned up and tweak in some manner to be useful.
Some are blended images of multiple textures. Many had to be changed from Cube Maps to Equirectangular Projections. I would sometimes just take a square clip of a nice paint splatter, embossed, chop it into 6 pieces and blend all 12 edges, over lapping each other so it can be used as a sphere. I've also done the reverse and taken globe shots, shredded them into a 100 odd shaped cut outs, made a random overlapping pattern of them until a 16384x8192 pic is filled.
Clouds aren't too tough, using the right combo of layers is more helpful as long as resolution is high enough. I also have to add my own snow and ice caps where I imagine they should be. Bump maps are tricky, and I might not have enough memory to make smooth ones. I think all-in-all most any texture can be used. Just keep tweaking things.
And really that's the key, using the Space Engine editor to make the best visual match for what-ever texture.
I humbly thank you for the complement.
CPU: AMD FX-8350 8 core processor 4GHz / GPU: GeForce GT 730 @ 1920x1080, 60Hz with 1GB adapter RAM / RAM: Patriot Signature 4GB 1600MHz 240-Pin DDR3 (only 2GB work, don't buy it) / Motherboard: MSI 970 Gaming MS-7693