I've just spent a pleasant hour exploring Saturn, which is free for a short time in the Mac App Store.
The GUI is based on LCARS (Library Computer Access/Retrieval System) featured on some of the Star Trek shows and films.
The app has a massive amount of data, and it's more than 1 GB to download. What you get are hundreds of images of Saturn and its moons, plus screens and screens of information and diagrams. There's truly a huge treasure trove of topics covered here.
Visually, the app is a treat, and it's easy to figure out how to navigate, even if you're not a Star Trek fan. I wasn't wild about the sound effects every time I clicked on something, but they can easily be muted.
Author Gilorien Barnhardt says he spent more than a year putting this app together, and it is easy to see why. If you're interested in the solar system, especially this unique ringed planet, mosey on over to the Mac App Store and download this app. Check out some of what the app offers in the gallery below.