Solar Walk 2.0 would certainly be the app favorite Darth Vader. This is one of the most epic creations for iPad, an app that puts a great 3D model of the solar system in your hands. If you liked the original, then Solar Walk 2.0 will fascinate you.
The application will take all the juice to the Retina display and the
iPad brings a few new features, among which includes more information,
"weight" to the planets, the planets internal structures...