RIM is doing a promotion in App World for all their BlackBerry Playbook astronomy apps. The only free offering is Dana Peters’ Planets app. Planets is a free 3D cosmos browser and visualizer that can help you pick out objects in the night sky.
The app focuses on our solar system’s planets as well as the major constellations. Set upon a background of the milky way, the solar system’s planets and constellations are displayed in a fashion allows you to find you bearings by lining the map up with a familiar constellation.
You’ll be out of luck if you can’t spot a constellation because there’s no magnetometer assistance or augmented reality style navigation. This gives the app the feel of classic discovery, like a planetarium.