Nicely done.
Shadow trick. Try two suns in the same place set to half the strength of your single sun and set one to a small soft shadow, say 0.5 and the other to maybe 5 or 10. You'll have to play with the settings but you can get some pretty cook effects with the shadow deepening more towards its centre. You can use even more suns as long as the total strength is not more than the original single sun.