Google Earth is a Web-based app that allows you to explore the world (and some of its strangest sights) in 3D via satellite imagery. Until fairly recently the best features of Google Earth were mostly limited to the desktop client--but now a free app is available for phones running Android 2.1 and above. It's a fun and educational app, but it requires a strong data connection, and some features may perform sluggishly on some phones with slower processors, such as the Droid.
At first glance Google Earth looks a lot like the Satellite layer in the Google Maps app, but with fewer features. It has no Directions option to guide you from point A to point B, for instance. As a result, you might be tempted to dismiss Google Earth as redundant--but it really isn't so. Google Earth does a few cool things that Google Maps cannot.
The most impressive feature is called Look-around. You activate the mode by pressing the little eye-shaped icon in the lower left of the screen. This toggles the app into a bird's-eye, 3D view that you can pan or pinch-and-zoom using the touchscreen; or, if you prefer, you can go to Menu, Settings, Use Hardware Sensors to use the phone's compass and accelerometer to control the view. The latter option feels very natural, as the landscape pans when you turn and tilt the phone in different directions.
I would love to see someone develop an Android-powered helmet or goggles to take full advantage of this feature--that would be supercool. Imagine the possibilities. (If you happen to know of something like this, I'd love to hear about it. You can e-mail me, or hit me up on Facebook or Twitter.)
Although Look-around can be a lot of fun (try the Grand Canyon, for starters), it is entirely dependent on a fast data connection. If you don't have a good signal, the app will crawl or blank out entirely. I wish it could save more data to the MicroSD card for offline viewing. The 3D rendering is very graphics-intensive, too, so the faster the phone's processor (think Droid X, Galaxy S, Droid Incredible, EVO 4G, and the like), the better the experience.
To find a specific location, just select Menu, Search and type or speak your search keywords. Press Menu, Layers to choose from several layers of data--Places, Businesses, Panoramio, Wikipedia, Roads, Ocean, and 'Borders and Labels'--to superimpose on your Google Earth view. I prefer to enable all of them.
The Places and Businesses layers are similar in that they provide icons you can press for more information. The implementation of features isn't as complete as in Google Maps, but you can launch links in the Web browser for more details.
The Panoramio layer, on the other hand, is one that you won't find in Maps--and it's a very interesting layer indeed. The Panoramio Web-based photo-hosting service places an emphasis on geolocation; it can read the EXIF data in an image file, and if the file contains GPS coordinates (photos you take with your Android phone are tagged in this way if you enable the feature in Settings), Panoramio automatically places the image on a map. You can also manually specify the image geolocation if the file doesn't contain GPS data.
Recently purchased by Google and integrated with Google Accounts, Panoramio also has a neat feature that lets users submit their geotagged photos to be part of the Panoramio layer in Google Earth. (You can use an Android app called Panoramio Uploader to send photos from your phone.) When you enable the Panoramio layer, user-generated-photo icons will pop up along the landcape, and you just click on an icon to view the image. Many of these images are quite spectacular, and they can give you a better understanding of the location at ground level.
The Wikipedia layer links specific locations to their corresponding Wikipedia articles. 'Borders and Labels' gives city names, state boundaries, and the like. Roads simply labels streets and highways. Ocean is a new feature that allows you to explore the sea; it contains some interesting information, but it does not have a lot of content yet.
Google Earth is a cross-platform service that is rapidly developing and adding new content, and the Google Earth app for Android provides a great new way to explore the world. I predict that as new Android phones with more-powerful graphics processors enter the market, Google Earth, with its 3D views, will emerge as one of the most popular Android apps.