Need some advice about makin planet game

I just start to learn ue4 but I dont have a guide or advice to make a planet game like star citizen
the last update show how they travel from space and landing into the ground

and I was found this video: *WIP* Ground to space Unreal Engine 4 Landscape - YouTube
that show how it’s workin in ue4 (but no tutorial)

I want to create planet look like dat (what software or how to make in material ?)
I only know how to make dynamic gravity but I dont know how to transition between planet and space and
how to make a atmosphere (like when go out of planet)

Please I need some advice where to learn how to make this what doc do I have to learn or some guide to make this

Thanks you

ps. sorry for my bad English