The term digital earth was coined by then U.S. Senator Al Gore in his 1992 book, Earth in the Balance, to describe a future technology that would allow anyone to access digital information about the state of the earth through a single portal. The concept was fleshed out in a speech written for the opening of the California Science Center in early 1998, when Gore was vice president. By then, the Internet and Web had become spectacularly popular, and Gore sketched a vision of a future in which a child would be able to don a head-mounted device and enter a virtual environment that would offer a “magic carpet ride” over the earth's surface, zooming to sufficient resolution to see trees, buildings, and cars and ...