Just a simple texture mod (file) to make the sky of Skyrim less B&W by shifting it's hue slightly into blue. Works perfectly with Milky way galaxy mod for Oldrim (as in pictures), link is here (highly recommended):
Skyrim Galaxy - Milky Way by Kriminalrus
Just use mod installer of your choice, or manually copy the skystars.dds file inside archive to "<Skyrim folder>\data\textures\sky" folder. In case you are using other sky mods (not clouds mods, but stars/galaxy ones), there is a chance of incompatibility, or in case their textures do not have alpha transparency, the file might get overwritten, or there might a be a seam over the sky. In that case, rename/backup&delete files "skyrimconstellations01.dds" and "skyrimconstellations02.dds" from the folder I listed above. It is possible you might have to do the same with "skyrimgalaxy.dds" if you are using other galaxy mod beside the one I listed (any that doesn't have alpha transparency galaxy texture).
Use NMM or delete manually the file "skystars.dds" you added earlier, and also restore the files you renamed/deleted. In case you didn't create a backup, you have only yourself to blame, I told you to do it :)
None that I know of, apart from not being compatible with mods that add sky textures with no alpha transparency.