Starship Asterisk*

Why are there no stars, galaxies, nebulas or anything else in the background whenever you see pictures of the Earth, Moon or other planets? Like today's APOD of Saturn's rings, great picture of Saturn, its rings and moons but the backdrop is completely black. Where is the starry backdrop?

The light from Saturn and the rings completely overwhelms any light from the stars.

It is a matter of Relative Brightness and shutter speed. When you have a large local light source (the planet) you need to have a relatively fast shutter speed or the light will cause over exposure. If you allow the shutter to be open long enough to pick up the much fainter Star Light, the light from the planet will be too intense to allow for any details to be seen. But if you use a faster shutter speed to allow for planetary details to be seen, there isn't enough time allowed for the ccd to pick up the much fainter star light.
People say the same thing about images from the surface of the moon. Although the actual surface is relatively dark (it is about the color of old Parking Lot asphalt) it only appears bright white in images due to the black surrounding. To see what is visible from the moons surface, go out to your local grocery store (during the summer months of course) and, while the parking lot lights are lit, look up at the sky and see how few stars you can see. Now imagine if the parking lot were as bright as it is at Midday. You might be able to pick out the 5 or 10 brightest stars only.