How Google Earth Works

What is Google Earth?

Google Earth is currently available for download as a desktop application, although you need to be connected to the Internet to use it. Every time you open Google Earth, it automatically connects to Google's servers, giving you access to terabytes of geographical, political and social data. For instance, you can view a city with certain "layers" turned on, including topographical information, population data and crime statistics for the area. The layers and all of the map navigation buttons, including zoom, tilt and rotate, are all located in the Google Earth frame.

The big deal right now is the basic version of Google Earth is completely free. Of course, this could change in the future. So let's all start by downloading the free version of the software located at Earth.Google.com while it's still free. If your computer runs Windows, Linux or Mac OS X 10.3.9 or higher, and it's fewer than five years old, you should have no problem meeting the system requirements. If your computer can't run the application, read on to find out what you'll be able to do once you update your equipment.

Once you open Google Earth and start moving around a bit, you'll immediately notice one of the biggest "whoa" aspects of the program: some of the information is 3-D, and the stuff that isn't 3-D is still a photograph -- there are no illustrated maps here. The baseline visual data comes from satellite imagery and aerial photographs taken by aircraft.

While Google Earth comprises an array of features that would probably take months to fully utilize, the basic features fit loosely into the following categories:

• Mapping/directions
• Local search
• Sightseeing

Basic Functions

The best way to get to know Google Earth is to start with a location and see what Google Earth will tell you about it. So let's start with HowStuffWorks headquarters in Atlanta, Ga. If you type "3350 Peachtree Rd. Atlanta, GA," into the Google Earth search box and click "Search," you zoom in from space to HowStuffWorks headquarters. You are now looking at a photograph of the location.

To get more information and turn the photograph into a real map, the next step is to turn on some layers. Available layers include dining, lodging, banks, roads, terrain, malls, grocery stores, gas stations, parks, transit, schools and geographic features.

To create a nice, functional map, you might just turn on the "roads" layer. If you zoom out a bit, you've got yourself a good driving map of the broader area surrounding 3350 Peachtree Rd. in Atlanta.

Let's say your little tour of Atlanta includes a stop at HowStuffWorks headquarters followed by a trip to the Georgia Dome to check out a Falcons game. A click on the Google Earth directions button reveals two slots: one for the starting address (3350 Peachtree Rd. Atlanta, GA) and one for the ending address (1 Georgia Dome Dr NW, Atlanta, 30313). Clicking "Search" reveals both written directions and a highlighted route on the map, which has automatically zoomed out to accommodate the entire route from HowStuffWorks to the stadium.

Google Sky

Google Earth wows users with its ability to fly to and from anywhere on Earth. In August 2007, Google introduced Google Sky, giving users the ability to actually take to the stars.

With one click of the mouse, a Google Earth user can switch to Sky Mode and reverse the perspective. With hi-res images from NASA, the Digital Survey Consortium and the Sloan Digital Sky Survey, Google Earth has put together an accurate and fascinating look at outer space. Users can fly around, just like in Earth mode, to search the far reaches of space.

As with the Earth portion, Google Sky has lots of layers you can display. You can find constellations by name or see them drawn out on your screen. The Backyard Astronomy layer references three astrological catalogs to give greater detail on some of the more well-known space objects. You can highlight galaxies, nebulae, star clusters and famous visible stars to get information on location, history, classifications and even links to NASA's database of information. There is also a Hubble Showcase that provides images taken from the Hubble Space telescope, along with some detailed data about the objects.

Two very cool features of Google Sky are the Moon in Motion and Planets in Motion layers. These show the paths of the moon and the planets across the sky from your given location on Earth. NASA took pictures once every hour for three months to make sure the paths were accurate. A slider bar lets you choose the span of time you want to view. Then, you just click to see the moon or planets move. If you click on the moon itself, the program pinpoints its location on that date, the phase, how far it is from Earth and how bright it may look in the sky. Click on the planets, and you can find out their size, distance and magnitude.

Google Sky also provides two very interesting tours of outer space. The User's Guide to the Galaxy takes you on a trip through a number of well-known galaxies. The Life of a Star tour shows the lifespan of a typical star, from birth to death. A fact list shows what happens to each star and how it fits into the cosmic soup. In both tours, you can either click on one at a time, or download it for one long trip through the universe.