How to script so the sun will always be the opposite of the player with an object in the middle?

I want to have the sun's position be dependant on the player's position relative to an object in the place. So no matter where the player moves, the object will be in the way of the sun. How can I pull this off? The object is anchored, only the sun and player is able to move. I want to modify the time and lattitude of lighting to achieve this.