SolarWalk, and their newer earthbound app, GeoWalk, are fantastic apps, and that's the most appropriate word. Not only are they great, but they show a fantasy world and universe, demonstrating not only what our environment looks like from different perspectives, but what it did or will look like, thanks to their time machine style controller! You can see where satellites are in space now, or in the past or future, which is fun and useful for astronomer types!
The apps are full of scientific information, and movies, too, so there's more than just a gee whiz element. These apps can be full features learning tools for today's children, who are wired to use apps first, and books second.
More than just planets, you can explore the moon, the stars and more! You don't have to wait until dark to explore our solar system!
Closer to home, GeoWalk let's you explore our own planet, with photos and facts about assorted locales and people.
It's no wonder Encyclopedia Britanica stopped printing their books. I've seen the future, and it's SolarWalk and GeoWalk.