Solar Walk is a nifty astronomy romp from the folks who did the popular Star Walk iPhone and iPad app. Instead of exploring the night sky and deep space, you get to tour our solar system in luscious 3D graphics. While the app is universal for the iPhone and iPad, the iPad version is breathtaking with crisp graphics and beautiful color.
Tapping on any planet will take you close to it, and you can use your finger to orbit the planet and see it from any angle or zoom. You can see the planets on any particular date and time, and speed up the animation to watch the planets in their elliptical orbits.
Tapping the info button gets you some information on all the planets, like size, gravity, composition and more. One omission is that the program doesn't tell you which planets are up for viewing on a particular night. You'll need Star Walk for that.