Gerhard Hahn didn't have time for telescopes this summer. He wanted to calculate the orbit and then the size of an icy little space rock just beyond Pluto in the Kuiper Belt, the solar system's maternity ward for comets. But 2001 KX76, as the hunk was affectionately named, had been discovered only in May. The subsequent few months' worth of telescope images didn't give Hahn nearly enough data to calculate what he needed. His obvious option was discouraging: taking new images would put off any eureka moments by years. So Hahn, an astronomer at the German Aerospace Center, got virtual. Running a computer program called Astrovirtel that scans and sorts archived images from the Hubble Space Telescope and the European Southern Observatory (ESO), Hahn and his team input KX76's space coordinates and hit pay dirt: an image taken by chance in 1982. "That gave us observations going back 19 years," says Hahn. With the old image plus six recent ones, calculating the rock's orbit and size was a snap--and yielded a surprise. KX76, says Hahn, "is most likely the largest minor planet ever found."
Technology has been good to astronomers. It has let them escape the cold and cramped basket on giant telescopes, where these sky watchers used to spend long and lonely nights exposing photographic plates to the dim light of distant galaxies. These days, astronomers hang out in a toasty control room while digital instruments collect the data. It also allows them to monitor data from telescopes in Hawaii or Chile or even space while sitting at their home computers. Now cyberastronomy is poised to take an even bigger step. Databases from space and terrestrial telescopes, containing everything from spectra of distant quasars to measurements of black-hole radiation, have yielded only a fraction of their treasures. Rather than leave those gems untouched, astronomers plan to mine them, hoping to make discoveries without ever pointing a telescope.
In October the National Science Foundation committed $10 million over five years toward this "virtual astronomy." The Europeans are also working on a virtual observatory, which astronomer Piero Benvenuti of the ESO calls "more worthwhile than building another [telescope]." Eventually, all the databases will be connected. The goal, says astrophysicist Alexander Szalay of Johns Hopkins University, "is to turn the Internet into the world's best telescope--a World Wide Telescope." They'll have a lot to work with. Astronomical data double every year. A single night's telescope run typically generates a few hundred gigabytes, while all the observations ever taken in, say, infrared wavelengths amount to a few terabytes. (One terabyte of data would fill 231 million pages.)
What might a World Wide Telescope discover? For starters, what's going on inside galaxies. Typically, one telescope snaps images in the infrared, another in visible wavelengths and another in ultra-violet. "Information about the different parts of the spectrum were taken with different telescopes at different times," says ESO astrophysicist Peter Quinn. But to understand the physical processes inside galaxies, you need to combine data from a bunch of wavelengths--for which a World Wide Telescope is ideally suited. Virtual astronomy could also jump-start studies of how fast the universe is expanding and whether it plans to do so forever. For that, you need to know how galaxies are distributed near and far, something that doesn't exist in a single scope's archives. The World Wide Telescope also promises to break the logjam in studies of how galaxies form. That requires terabytes of data to capture galaxies in their infancy, childhood, middle age and dotage. As virtual astronomy gets real, the discovery of the largest minor planet in the solar system will be only one small step along the road to an online universe.