For ardent sky watchers, it is a dream come true. The Sloan Digital Sky Survey, funded by the National Science Foundation and other organizations, is the largest, costliest astronomical survey ever launched. It is still underway, and the project has already generated digital images of more than one million galaxies—that’s the good news. The bad news is that professional astronomers are hard pressed to keep up with the incoming flood of celestial data.

To work around that problem, a group of scientists from Oxford University and the University of Portsmouth in England, and from Johns Hopkins University in the U.S., teamed up and formed www.galaxyzoo.org. The unusual charter of the website was to solicit the help of the general public in the job of classifying the galactic images into basic categories. The researchers decided to try farming out the initial classification of galaxies into their two primary forms: spiral galaxies, with stars forming mostly circular disks, such as the Milky Way, and elliptical galaxies, with more randomly oriented stars in bunched, spiral-free patterns.

Why not simply use computers for the task? According to Daniel Thomas of Portsmouth University, “Computers can do this classification automatically, but humans are far more accurate. It’s like trying to distinguish between male and female faces—no computer algorithm will do this as accurately as a person.”

Visitors to the Galaxy Zoo sign up and take part in a simple tutorial session. After that, they are off to work. The page gives them a collection of images, and they are free to sort to their heart’s content.

The response has been overwhelming: The Zoo went online a month ago, and already has more than 85,000 amateurs helping with the work. The Sky Survey was forced to upgrade its servers immediately, after the first day on line resulted in blown circuit. At times of peak usage, the Galaxy Zoo serves up as many as 60,000 images per hour to happy stargazers all over the world.