I think that you have it backwards. In the upper atmosphere, you CAN see stars. As you go higher in altitude, the air gets thinner. As the air gets thinner, it ability to scatter light diminishes. So, as you go up, eventually the air becomes so thin that the day time sky loses its blue color and becomes completely transparent (just like it is at night on the surface). At that point you can see the stars even when the Sun is out. -------- Shaneaproductions, That is a matter of the lack of range in sensitivity for the instrument. If the films exposure were long enough to capture the stars, then the object that is in full sunlight would be over exposed. If the object in question were exposed properly, then the film would not capture the stars. Take a look at the photo that I attached. (The only editing that I have done was to change its size.) Notice that you can’t see stars in the background. This is because they are too dim for the camera to capture without over exposing the people. You can test this for yourself. Just take a flash picture of some nearby object silhouetted against a starry sky. You won’t see stars in your photo either. If were at a high enough altitude to see the stars in the day time, you would still have trouble seeing them if you were looking at a bright object for the same reason. However if you were not looking at a bright object, then your eyes would adjust to let you see the stars.