Works with Unity 5+
With the two included shaders, the earth has a day/night cycle depending on where the light is in the scene. The strength and color of the city lights can be can be modified in the inspector. Also contains clouds that are separate from the earth model.

Both the earth and clouds have separate rotate scripts so they may be manipulated separately.

Package includes:
2 Shaders
2 Scripts
4 Prefabs
2 Skyboxes
1 Example scene

The main Earth texture is 16200 x 8100.

Here the other assets from my planetary series:
Moon
Mars
Venus
Mercury

Take a look at my other assets HERE.