"Google Earth" obtains all its maps from the internet. The advantage is that a huge stock of maps is available, and streadyly up-to-date. To view terrain and roads (maps, aereal photos, satellite fotos) one needs an internet connection. At home it is no problem.

But what happens when I want to use "Google Earth" out of the home and I've no mobile internet?

YES: Without internet "Google Earth" cannot load new maps, but the former visited maps stay in the computer.

The GPS reception works all over the world and is independent of the internet. GPS is an independent system.

Pure web applications (like  Virtual Earth and Google Maps) loose their maps without internet connection. Not as "Google Earth" - it remembers images and maps once shown in the screen in its so called Cache memory. As long as this cache is'nt full all recently "overflown" Areas are still available.

If you revise calmly at home all interesting areas (you plan to visit on a tour) in "Google Earth" with an active internet conmection, all this maps stay available in "Google Earth" even after disconnecting the internet. Now you may take the Latop into the car or on the boat and will have all necessary maps "in the bag". For the GPS navigation internet itself is'nt yet necessary.

Now also with Cache Manager

In the new version 3 the tool "Cache for Google Earth" is entirely integrated into "GPS for Google Earth" - without surcharge. This gives you the oppotunity to manage different offline maps stocks. It's no longer a blind chance, when Google Earth deletes older maps cause of a full cache. In fact you may exchange offline cache copies with other computers.