By BRUCE SCHECHTER

About two years ago a large group of astronomers began to assemble what some of them were calling "the world's best Telescope." Their ambitious instrument is still far from complete, but they recently took it for a test run. Within minutes, to their joy and astonishment, they had discovered three or four brown dwarfs, objects that occupy the niche between planet and star. "It gave me shivers when I heard about it," said Dr. Alex Szalay, a Johns Hopkins astronomer who is one of the telescope's chief architects.

It wasn't the brown dwarfs themselves that excited Dr. Szalay; hundreds of them have been discovered in the past decade. But he and many other astronomers believe that the means used to discover these objects heralds the beginning of a new era of astronomy, and even a new era of science.

The telescope that Dr. Szalay and his colleagues have constructed is not built of glass and metal. It is a virtual observatory, consisting of terabytes of data collected by dozens of telescopes on Earth and in space, and the software necessary to mine these data for scientific gems.

Like much of the rest of science, astronomy has been the beneficiary — and victim — of Moore's Law, which states that the capacity of computers and other silicon-based devices like charge-coupled devices, or C.C.D.'s, doubles every 18 months. (The C.C.D has largely replaced photographic film in astronomical cameras.)

Projects like the National Virtual Observatory, which was created in response to the tsunami of data that is threatening to drown astronomers, is creating a new branch of science, Dr. Szalay believes.

Science, he points out, was "originally empirical, like Leonardo making wonderful drawings of nature." He continued: "Next came the theorists who tried to write down the equations that explained the observed behaviors, like Kepler or Einstein. Then, when we got to complex enough systems like the clustering of a million galaxies, there came computer simulations, the computational branch of science. Now we are getting into the data exploration part of science, which is kind of a little bit of them all."

Because its primary tools are computers rather than giant, multimillion telescopes, this new form of astronomy has the potential to democratize science. "If at the same time most of the telescopes in the world are actually putting all of their data online with proper explanations," Dr. Szalay said, "then it doesn't matter where somebody is sitting, they can access all the data — either somebody in Baltimore, or somebody from Africa who got a Ph.D. in the U.S. and returned there and doesn't have access to a telescope but suddenly has a bunch of students. They can actually get to first-class data."

In the past 25 years the number of C.C.D. pixels in all the world's telescopes has increased by a factor of 3,000, with each pixel acting as a miniature astronomical instrument. The result, Dr. Szalay says, is that the total amount of astronomical data collected every year is doubling even while the amount spent on astronomy remains constant.

"We are getting overwhelmed," Dr. Szalay says. "With this explosion it's not just that individual telescopes are getting more and more data, but also the threshold gets lower, so that more and more groups are putting big cameras on their instruments. Even amateur astronomers today can generate gigabytes of data per night by attaching a digital camera to their telescope."

The problem is how to mine this vast store of data for the riches it almost certainly contains. Astronomers have been busy over the past couple of decades compiling complete surveys of the sky, encyclopedic catalogs of millions of astronomical objects viewed at many different wavelengths. These surveys exist in about 10 different spectral bands, from X-rays to the infrared, with each survey giving a different view of the universe.

The surveys contain about 100 terabytes (one terabyte is 1,000 gigabytes) of data, roughly five times as much as the Library of Congress holds. Unlike the Library of Congress, however, this information does not reside in a single place.