DAY and NIGHT Texture on Planet Earth

Hi everyone;

I'm making Planet Earth on Unity. So I use Materials to put the texture on the 3D Sphere and i set a Rotation on it for day and night cycle.

Now the question is: I want to do 2 texture, one for the DAY SIDE and another for the NIGHT SIDE.

I want that the texture of the Night Side fade to the Day Side and the Day Side fade to the Night Side.

How i'm suppose to do it? I really have no idea how can i release it. And i'm using Playmaker for the Scripts.

Thanks you.