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Star Walk for IPhone

I have a soft spot for any science-related app out there, but my favorite thing about owning an iPhone and iPod touch is playing with all the astronomy-themed apps from the App Store. I have a few of them on my phone, including some I've reviewed. There are so many things to explore in our universe, and many apps can help you get started.

One such app is the $3 Star Walk, an educational planetarium app from Vito Technologies aimed at both kids and adults. The app launches with the Sky Live screen, which shows you the Sun, the Moon, Venus, Mars, Jupiter, and Saturn. The screen shows when the Sun and each of those planets rises and sets, as well as the elevation angle of each of those objects. For the Moon, it shows the current phase. Tap on one of the arrow buttons on the bottom left or right of the screen, and the date in the upper right corner changes to the previous or next day, depending on which direction you choose. As you cycle through the days, you can see the Moon phases change and the information for the other objects featured on the screen change as well.

To escape the Sky Live screen, tap the X button in the upper left. You'll see a sky view of the stars and other celestial objects. Four buttons occupy each corner of the screen: a bear-paw-shaped button in the upper left, a clock button in the upper right, a magnifying-glass (or search) button in the lower left, and another bear-paw-shaped button in the lower right. (Before getting into the various functions of the buttons, there's fun news about this app for iPhone 3GS owners: Tilt your iPhone skyward, and you'll activate the Star Spotter view, which shows you what you are looking at in the sky from where you are at the time. This is a great way to learn about the universe in a more interactive and realistic way, instead of just abstractly by tapping buttons on screen to give you more information about an object that may not be relevant in relation to your position on Earth. To deactivate this mode, touch the screen again. The Star Spotter mode, which relies on the GPS capabilities of the 3GS, doesn't work on the original iPhone, iPhone 3G, or iPod touch.)

When tapped, the bear-paw button in the upper left of the screen gives you two choices: you can either go back to the Sky Live screen or go to information about the app, contained in five concise screens. I recommend reading through them to get an idea of how to navigate the app. Having said that, I will gladly acknowledge that the app is very intuitive, and you can figure out how to navigate it just by playing around with it.

The magnifying-glass (or search) button in the lower left of the screen flips the screen over when pressed and displays four choices for you at the bottom: you can choose to view constellations, the Solar System, Messier objects, or stars. You can also search for objects through the search box. This box is handy, especially if you know how to spell the object you're looking for, but I'd also like to see an alphabet listing somewhere on screen so I could choose a letter and be taken immediately to the various objects that begin with the letter I choose. I can currently type a B in the search box to get to all the star names beginning with "b," for instance, but I also get star names that have the letter B somewhere in their name. Having a more precise way to get to objects would save users time.

One cool thing about the search feature in this app, though, is that you can type a name or letter in the search box, and notification badges will appear next to Constellations, Solar System, Messier, or Stars that denote the number of items in each category that match your search.

When you choose an object from a list, be it a constellation, a planet or object in the Solar System, a Messier object, or a star, the screen flips again and shows either the object name in green or the object itself circled in a green, animated circle. Tap on the info (i) button in the upper left to get more information about the object. A lot of the objects have very little information beyond just their names, but you can tap on the W button in the information box to go to the Web (a Wikipedia page) to find out more about an object. While not available in every information box, the W button worked seamlessly for each object I tested. The only drag about choosing to go to the Web is that you leave the Star Walk app and launch the mobile Safari browser, with no easy way to get back to Star Walk for continuing your discoveries. An update that Vito Technologies is working on now, version 4.0, makes the information about each object more detailed from within the app itself, thus limiting the number of instances you need to go to Wikipedia. The new version is not yet available on the App Store, but I've seen a preview and can say the changes improve the app.

Also, some of the names of objects you can choose are listed in white or grayed out. Don't be fooled, though; you can click on the grayed-out ones and still get information about them. There seems to be no rhyme or reason as to why some names are grayed out and others are in white.

After trying out the info button, you can tap on the clock button in the upper right to reveal the Time Machine. That shows the current date and time. Flick upward on the Time Machine timeline, and you can view the object of your choice the way it appears at various points in time. This is really cool for seeing how Venus, for example, travels on its orbital path in relation to Earth and the Sun as time goes by. You can speed up or slow down the rate of the Time Machine. This feature is pretty sensitive, though, so you're more likely to have to slow it down than speed it up. Tap on it to stop it. You should see the word now next to the date and time display. Tap it to return to the current day and time.

When you've finished learning about an object, tap on the magnifying-glass icon again to take you back to the list of objects you chose from. If you're finished looking at objects altogether, tap the Done button. The problem with doing this, though, is that you're taken to the screen of the object you just learned about, with an info button in the upper left instead of the original screen's bear-paw button. To get back to the original screen, you need to tap the other bear-paw button in the lower right, tap the globe button, tap the constellation button in the lower left of the 3D globe screen you just loaded, and then you're back to home base, as it were. An easier way to get back to the original screen would be much appreciated, in case a user wants to reference the app's Sky Live or information screens. Luckily, this problem will be tacked in the version 4.0 update.

Speaking of the 3D global view of Earth--it's awesome. There are a few apps I know of with a similar type of globe view of Earth: The free Planets and Google Earth have one. What makes the one in Star Walk different is that it takes you from the perspective on Earth as you look at the sky to the perspective of space as Earth is seen from it. The effect in Star Walk is neat--it's one I repeatedly invoke just for fun. You can also turn the globe by using various finger gestures.

You can have the app read your location automatically (an option you choose the first time you launch the app), or you can set a location yourself. It would be nice if the app asked to use your current location each time you launched Star Walk, or at least gave you the option to turn it off. You can tap the magnifying-glass button in the 3D globe view to get a list of cities around the globe in order of their distance from your current location. But if you set a location somewhere in Argentina, for instance, the distance measurement for the cities listed is still the distance from your current location, not the distance from the new location in Argentina that you chose.

Accessing information through the buttons on screen isn't the only method you need employ. You can just tap on screen anywhere and the object will be surrounded by the green, animated circle I mentioned earlier; then you can tap the info button to learn more about it.

There are other useful and neat features you can access through the bottom right bear-paw button: the tools menu lets you set options, one of which includes a night-vision mode; and a book button takes you to a screen on which you can view a picture of the day or create bookmarks to your favorite space object. You can even e-mail bookmarks to people. When I tested this, however, I got strange results. I opened the e-mail on my iPhone. When I tapped on the name of the bookmark in the e-mail, Star Walk started to launch but then quit, and I was taken back to my iPhone's main screen. When I tapped on the Open Bookmark In Star Walk link, my phone tried to connect to the App Store but failed. (When I connected to the App Store through the App Store app, however, I connected without a problem.) From my desktop, the Open Bookmark In Star Walk link brought me to the App Store page for it in iTunes. The e-mail also contains a picture of the object you sent.

Normally, I'm not fond of the sounds built in to various apps, but the sounds in Star Walk are exciting. They remind me of the sounds coming from The Enterprise computer helms in Star Trek: The Next Generation, but the sounds go a step further than that. When I use the app with the sounds on, I feel as though I've finally entered into the future promised by all the great science-fiction novels and movies I've enjoyed in my lifetime so far. I become rather elated as I tap buttons in this app. In the tools menu, you can turn the sound off if you prefer, and adjust its volume.

Star Walk is a great planetarium app. It has a few wrinkles, but the developers are making the following updates to the app in the forthcoming version 4.0: tweaking the Sky Live screen to be more descriptive of what you see on it (such as naming the planets shown instead of leaving you to figure it out for yourself); changing the on-screen buttons to fix the problem I mentioned earlier about not currently having an easy way to get back to the Sky Live screen; adding more information in the app itself about objects; and tweaking the Time Machine feature a bit.

I recommend this app for anyone interested in learning more about objects in space and Earth's relation to them. And the app is intuitive enough for kids to easily navigate. For $3, you get the universe in your pocket. So get outside and see what you've been missing.

[Sue Voelkel is Macworld's managing editor.]

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