This package provides these realistic looking planets: Earth, Mars, and the Moon.
Doesn't work with Universal Render Pipeline in Unity 2019
Features:
- Ready-to-use prefabs that can be dynamically instantiated.
- Highly customizable shaders with normals, night lights, specular, and inner atmosheric scattering effect.
- Separated clouds and clouds shadows.
- Outer atmosphere shader with scattering effect.
- High polygon sphere (about 40000 triangles)
- A set of 8K textures
- Milky Way skybox
- A sun lens flare
- Included demo scene that shows how everything works.

Earth Flyby Video
All Planets Video
Web player demo
Documentation for Unity 5 version
Documentation for Unity 4 version
Forum thread