Friday, February 1, 2013

Star Walk for iOS Review

Star Walk isn't a camera app (actually, it kind of is) so much as it is a pseudo-camera app. The program has been near the top of the educational category in the Apple Apps Store for quite some time now. If you have astronomical inclinations, this is a good program to add to your iPhone.

Star Walk's 'virtual augmented reality' interface

I describe this as a "pseudo-camera" app because it behaves like an augmented reality camera app, though it really isn't, at least not most of the time. Instead, the program cleverly combines your location data, the electronic compass, and the position sensors on your phone to create a virtual view of the sky. It works brilliantly. If you pan the phone across the sky, the screen accurately simulates the starts and constellations that you yourself are seeing with your naked eye. There is also a "true" augmented reality feature where the app further combines the image data from  the camera to give you a real time view of your surroundings with the star map overlaid. It's a lot of fun, but it's usefulness is quite limited in the dark, as the iPhone camera isn't sensitive enough to pick out stars to be of much use for actually navigating the sky.

You need a data signal and Location Services activated on your iPhone in order for the automatic tracking to work. I tested the program in a rural part of town where the cellular service isn't as dense as it is in the city, and the program worked fine. I've heard that some people have had trouble obtaining accurate bearings, so I suspect that the accuracy will depend on how good your cellular service is.

(Note: I think a video demonstration would work better than words, but as is usual here in Vancouver in the winter, we have not had clear nighttime skies for quite some time. That and I have a nasty case of bronchitis this week, so I'm not heading out into the cold again, not for quite some time.)

You can adjust which magnitude stars get displayed.

There a few display options (constellations, satellites, TelRad, spectrum) but the most immediately useful one is the ability to adjust the display to match the visibility of your night sky. Because I live in Vancouver, light pollution cuts down all but the brightest magnitude stars. By matching the app display to the number of starts that you can see with the naked eye, it makes navigating and finding celestial objects easier. If you want to get all Carl Sagan about it, the app also has a fitting ambient soundtrack that you can play in the background. There's even a night time mode to make viewing easier in the dark, which I found to be very useful.

Night mode.

Where Star Walk shines with photography is in its ability to help you quickly locate celestial objects when you are out in the dark. This is especially useful for deep sky objects that are just on the cusp of your visual perception (e.g., the Andromeda galaxy), which are harder to find and locate. A great thing about Star Walk is that you can just slap your phone flush against your camera's LCD screen. You can then align your camera according to the display on your phone.

(Digression: Presumably a more advanced astronomer would have an equatorial mount  and a more precise way of locating objects. There is another way to cancel out the rotation of the earth, and that is to use a program such as DeepSkyStacker in order to align multiple shots into a cohesive image.)

As is fitting for an "educational" app, the program will bring up information when you tap on the object, and also includes the ability to adjust the time so that you can visualize how the sky will look on another day. There's galleries to browse when you're not looking up at the sky and the way that the program is integrated into Twitter is both creative and fitting with Star Walk's astronomical underpinnings.

More serious astronomy buff's will find Star Walk to be a tad bit on the limited side for serious stargazing, but overall, the program has a nice looking presentation and simple operation that the layperson can immediately get into.


  • Pretty interface
  • Simple operation
  • Great for getting kids interested in astronomy
  • Reasonable price for a paid app


  • Less useful for the advanced astronomer

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