add blue sky over a stary sky box

hello, i know the question is a bit odd but i am atempting to make a space gmae and want it so when you aproach a planet you get a blue sky somewhat gradualy and when you get away you see a skybox of space, currently i have it to set it to a uniform color but that makes it hard to know when you are turning since there are somethimes no reference objects in view. any ideas on how to gradualy add a blue sky over a starry skybox. i apreciate your time and thanks in advanced.