How do old iPhone favorites hold up on the iPad? In our From iPhone to iPad series, TUAW revisits iPhone applications that have transitioned to the iPad. We look at their latest incarnations and see how the new measures up to the old. Today, TUAW looks at Star Walk.
I first encountered Star Walk last summer at an O'Reilly Foo Camp meet-up. "You want to see an app that really takes advantage of everything a 3GS can do?" asked one of the attendees. "Try Star Walk." I dutifully scribbled down the name and, when I returned home, I picked up a copy at the App Store.
True to the advice, Star Walk really impressed. It's a kind of "virtual window" application that you use at night. You look "through" the 3GS to the sky behind it and see a live view of the constellations the 3GS is pointing at. Move the 3GS down out of your field of view, and you see the real night sky. Move the 3GS back in front of you and it explains exactly what you're looking at.
That's because Star Walk was one of the first applications that took advantage of the iPhone 3GS's built in magnetometer. The sensor that powers the onboard compass allows apps to retrieve magnetic north readings. Star Walk uses the magnetometer to determine which way you're looking -- not just your position. And it uses that bearing information to display the correct portion of the night sky.