I only got halfway through Blender Guru's video but I recommend watching it to learn about Blender's node system and texturing if you're new to 3d like I am. This is literally just 3 spheres, 2 with NASA images and bump maps on them (Earth and the clouds) and the last one for the blue atmosphere which is just transparent.
Blender Guru also teaches you how to add city lights to the dark side of the Earth, how to add a space skybox and a sun and moon in the video
All the required textures are in the description on youtube
