Didnt do anything specific in that regard, its a just a standard UV sphere with a (2:1) texture map. I did run in to that issue when trying to export (bake) a procedural gas planet texture map, but its pretty trivial to fix the texture map in photoshop afterwards. This is just an entry level project i did to learn the basics of blender, after 25 years of using 3DsMax only. Took a good while to render on my new pc so i thought i should share it before deleting it localy.