In the main hall of the hands-on science exhibits at the Cape Town Science Center in South Africa, a lifeless, tattered globe stands under naked fluorescent bulbs, all but ignored by children passing through on school tours.
Across a sunblasted courtyard and up a dingy staircase, another globe -- a digital globe -- stands in a darkened room. This globe is a shining sphere of light. Children stand awe-struck; adults of a certain age may be reminded of images like Apollo 8's Earthrise photograph, while Tolkien fans of all ages will recall the spherical, swirling "palantír" of Saruman in "The Lord of the Rings" (forged in the days when Middle Earth was still flat).
Until recently, cost and technical limitations have largely confined these modern spheres to institutional settings like science centers. But as technology improves and prices fall, it's growing more likely that a digital orb will someday arrive in a classroom or boardroom -- even a living room -- near you.
As the name suggests, a digital globe is a spherically shaped display screen. Like the old-school globes once common in classrooms, digital globes vary in size, but a typical model is about 24 inches across. Unlike the globes of your childhood, the image on a digital globe can be changed with the touch of a button. Controlled by a keyboard or tablet computer, a digital globe can toggle between familiar, static images, like the world's political boundaries, topography or vegetation. It can animate complex phenomena, like the formation of weather systems, the effect of global warming on wolverine habitats or the annual pulse of sea ice. It can display the surface of the moon, the churning azure cloudscapes of Neptune or the celestial globe -- the night sky.
A digital globe can illuminate the human planet: wars, colonization, the formation of diaspora, modern trade flows or air traffic. It can also help teach math, play games, show movies or serve as a blank canvas for one's inner, spherical artist. Michael Starobin, 44, a multimedia professional and the producer of seven spherical films, says this brave new world is limited by only one rule: "Respect the roundness."
Easier said than done. For centuries mapmakers have tried to smooth a round planet onto flat maps with as little distortion (and controversy: see Mercator, G.) as possible. Makers of globes (including, we forget, Mercator himself) confronted an opposite problem: how to efficiently place or print information onto a spherical surface.
For digital globe engineers, the holy grail remains a spherical computer screen. Edward R. Tufte, the author of "The Visual Display of Quantitative Information," is enthusiastic about the potential of digital globes to remind us of earth's offline realities -- "by forgetting about the 3D whole Earth, flatland economic optimizing leads to global pessimizing" -- as well as the possibility that a company like Apple will someday soon roll out a Retina-caliber spherical display. Until that happens, digital globes will rely on optical projectors. But how do you project an image so that it lands equally bright, focused and undistorted on the surface of a sphere?
There are various optical solutions. But the broadest distinction is whether the image is externally or internally projected. The market for externally projected globes -- e.g., Science on a Sphere, the popular devices installed at around 85 institutional locations -- is limited by cost, the fixed nature of the installation and the fact that a viewer who gets too close may find herself contemplating one of the memorable descriptions of the Ottoman ruler Suleiman the Magnificent, "the shadow of God on Earth."
Science On a Sphere Earth System Overview
Rather, the digital globes that may soon break out of the museum use internal projectors. Even then, they cast an imperfect light upon the world. A small portion of the extreme Southern Hemisphere (i.e., around the South Pole, if you've chosen to align the Earth's axis vertically) is blocked by the projector and base. Brightness, while vastly improved, also remains an issue.
Beyond those, the biggest obstacle is cost: around $43,000 for a 24-inch diameter HyperGlobe from iGlobe of Franklin, N.H.; $40,000 for a 32-inch OmniGlobe from ARC Science of Loveland, Colo., or $21,000 for a 24-inch Magic Planet from the market leader, Global Imagination of Santa Clara, Calif.
These prices, though, are falling. Mike Foody, the C.E.O. of Global Imagination, says that he hopes to have education-discounted prices down to $2,500 within a year or two. If he succeeds, that would be within the price point of other high-tech classroom equipment, like interactive whiteboards.
Global Imagination's Magic Globe demonstration.
Not every school has been content to wait. Since 2007, the Mayo High School in Rochester, Minn., has used a digital globe in earth science lessons. Lawrence Mascotti, director of the school's planetarium, noted that children today display such confidence with digital media that he regards the globe as a means for teachers to "play" at the students' level, rather than vice versa.
He also finds the sphere a "more democratic" educational tool than textbooks or computer screens. While some children have difficulty with language-based concepts and mental manipulation, the digital globe works for nearly everyone, Mr. Mascotti says. "It's simple. The mind follows the eye."
Digital globes have obvious relevance to earth sciences and astronomy. But their potential in other subject areas is already being exploited. In China, where digital globes have found particular favor in schools, less than half the lesson plans are science-based, said Mr. Foody (in an ironic reversal of globalization's typical tide, around 80 percent of Global Imagination's orders are bound for China). Chinese schools use them mostly to teach social sciences, like the geography of religion and language, and history.
Whether the digital globe is used to teach earth sciences and astronomy or social sciences, the display itself generally represents Earth (or another astronomical body). But Math on a Sphere, a National Science Foundation-financed project, treats the digital globe as a generic spherical screen. In the study's workshops, children use math skills to build and manipulate their own spherical creations. The results -- which suggest art as much as math -- will be applicable to classroom-based globes, too.
Sherry Hsi, a project investigator at the University of California, Berkeley, observes that however technically sophisticated children today may seem, opportunities to instruct a computer directly are increasingly rare. With Math on a Sphere, children give a computer specific graphical instructions, and manipulate the results live on the "uniquely compelling" sphere. According to Dr. Hsi, many parents have been particularly surprised by the interest their daughters have taken in this literally three-dimensional programming.
Digital globes already appear in the occasional corporate lobby, perhaps an infinitely adaptable replacement for tired time-zone clocks. Upstairs, a digital globe could take on more sophisticated deployments: summarizing sales data or market penetration, say, or resource allocation, or the locations of globe-trotting team members.
It is after hours, though, that digital globes may find the most unlimited potential. If prices bring them into the realm of home use, then a globe may provide a luminous living room centerpiece for adults and an educational tool for children. Think too, of music visualizations, digital aquariums, geotagged vacation photos, real-time flight tracking of your spouse's trip, Risk-style "board" games. Or the mischievous, blinking digital eye that followed trick-or-treaters as they walked up to Mr. Foody's house on recent Halloweens.
When it comes to digital displays, the iPad has set a high bar."High,"Mr. Foody said. "But flat."
This article originally appeared in The New York Times.