Apple's Star Walk, a planetarium app for the iPhone and iPad, brings the stars and planets into your hands. There are about two dozen other planetarium apps in Apple’s App Store but this one stands out with its responsive interface, user friendliness, and artful display.
As you start up the Star Walk app on your iPad or iPhone, it asks your permission to obtain your location like any other location-based app. Then Star Walk gives you a handful of quick, celestial facts on your coordinates such as phase of the moon, sunrise, and sunset.
Next, users are given a representation of the sky based on their location and time at that moment. The controls are as intuitive as you would expect. You move around the sky with your finger and you can even see below the horizon. Zooming in and out is done with a two-finger pinch.
There are some very nice touches such as lens flares when the Sun moves into view, and constellations appear with their graphical representations of their names superimposed over them. It also includes small but welcome details such as occasional shooting stars and the twinkling of distant stars. A cosmic but unobtrusive soundtrack also plays in the background. Collectively, these elements provide a very engaging presentation.
Users who are just beginning to learn astronomy will appreciate that the Star Walk app tracks their orientation and displays the sky in any direction the instant the iPhone is moved into a vertical orientation. Although Star Walk may sound like a toy, it actually has very useful features like setting a time in the past or present to view the sky. You can also accelerate time in increments of minutes, hours, days, or years with a flick of the finger so you can watch how the celestial bodies move through the sky.
You can also simulate varying levels of light pollution to show more or fewer stars. With just a tap on your iPod or iPhone's screen, you can get details and statistics on any of the 9,000 celestial bodies in the app. The Star Walk app is light on technical features and details and will probably not be an astronomer’s app of choice, but for the rest of us it provides an informative walk through the stars.