Google Earth has hundreds of terabytes of geographic data. But how does Google Earth search work ? How does Google Earth take pictures of cities ? Why are some parts of the globe blurry, and others crystal clear?

All your questions about Google Earth are answered by Mark Aubin, founder of Keyhole, the company that became Google Earth. Mark explains everything from with the history Google Earth to how the imagery comes from a variety of sources and is mosaic-ed together.

How Google collects images for Google Earth

Google collects imagery via airplane and satellite, but also just about any way you can imagine getting a camera above the Earth's surface: hot air balloons, model airplanes - even kites. The traditional aerial survey involves mounting a special gyroscopic, stabilized camera in the belly of an airplane and flying it at an elevation of between 15,000 feet and 30,000 feet, depending on the resolution of imagery you're interested in.

After taking the imagery, Google then adds layers of information like country and state borders and the names of roads, schools, and parks. This information comes from multiple sources: commercial providers, local government agencies, public domain collections, private individuals, national and even international governments.

Related: List of High Resolution US Cities pictures

Source: How Google Earth Works