It's a striking portrait of a handsome couple. But if they are floating in space, where are the stars? Shouldn't we see thousands of stars in the background, maybe even the Milky Way? This solid wall of black sky in so many images from space is the source of confusion--not to mention conspiracy theories.

The answer is pretty straightforward. The stars are there. In fact, if you could physically ride along with Chang'e or any of the other spacecraft you'd see the stars in all their glory. The issue is a photographic one. Cameras have a much more difficult time than your eyes do when it comes capturing widely different levels of light. It's simply very difficult, often impossible, to correctly expose a photograph when the scene contains both very bright areas and very dark ones. A simple experiment: try taking a picture of a bright moon in a dark sky. Chances are, even though you can see both the moon and the stars with your eyes, if you've set up your camera to expose the picture so that the moon shows up clearly, you won't see any stars near the moon's bright disc in your picture.

So when the Apollo astronauts were bouncing across the moon's brilliant horizon the sky behind them looked black. The same is true for images from robotic spacecraft in deep space: Saturn is dazzling, not only aesthetically but physically as well.

All that said, there are exceptions. Sometimes, those exceptions make for the most amazing images. When conditions are just right the stars do show up, as in this view of Saturn's moon Enceladus from the Cassini spacecraft.