The latest NASA picture of Saturn shows the planet is a very sharp sphere like a marble? How can that be?

all those pictures are computer generated from bits and bytes of the sensors. they are digital cameras not photographic.

ALL images have resolution limits. things too small and close together to be identified.

How far does the fuzziness of the atmosphere extend? How big is the planet? What's the resolution of the camera? There comes a point when the atmosphere is too thin to scatter and reflect light, and that can be quite a sharp boundary. Look at pictures of Earth from space. Earth has an atmosphere but it still looks like a sharp edged sphere.

Saturn's atmosphere would appear fuzzy if the picture had been taken much closer to Saturn. Instead, it was imaged from far enough away the its edge _looks_ sharp. This is the same as a distant mountain on Earth looking very sharp to the naked eye, but quite rough when you are actually climbing it.

Also, Saturn is lit from behind in this photograph, which causes a number of unusual lighting effects. Its thin upper atmosphere is lit up from behind so that it looks like a sharp line, when really it is quite fuzzy.

[Edit] I presume this is the image you're asking about:

http://apod.nasa.gov/apod/ap131113.html

Remember- Cassini orbits at ranges of up to tens of millions of miles.... from that kind of distance, a planet 54,000 miles in diameter *does* look very sharp, but, as you get closer, the "fuzziness" of clouds begins to be apparent.

Earth is no different - from the moon, a mere 1/4 million miles away, it's edge was very clearly defined; but from Low Earth Orbit, you can see the atmosphere thinning on the horizon.

If Cassini was orbiting a few hundred kilometers from Saturn, it would indeed appear fuzzy.

But since Cassini is anywhere from 19,000 to 150,000 km from Saturn, the images appear clear.

Where was the picture taken from? Hubble? Earth Based Camera?

The resoultion is not good enough to show that detail.

do you have an idea how far away Saturn is from the Earth?/

Only a Camera in Orbit around Saturn whould show that amout of detail.