Berlin (dpa) — Most people visit a planetarium only once in a blue moon, but they see and marvel at a starry night sky much more often. But those with little knowledge of astronomy probably don’t know what exactly they’re looking at. That’s why it’s worth installing Sky Map, a free app that turns any Android smartphone into a pocket planetarium. With the sky map in hand, it’s no longer difficult to identify stars, planets, and nebulae. You can enter the name of a planet, star or constellation in a full-text search, then move your smartphone around the night sky until a search circle with an ar…