Burdened with an avalanche of astronomical images and not enough manpower to sort through them, an international consortium of institutions is turning to ordinary Web denizens for help. The Galaxy Zoo 2 project builds on the original Galaxy Zoo, launched in 2007, which presented volunteers with images of galaxies for classification as elliptical or spiral—and, if spiral, clockwise or counterclockwise. The new iteration, launched this week, follows up on that basic data set by probing galaxy structure more deeply. Galaxy Zoo 2 throws a quarter million images of bright galaxies to armchair astronomers for examination: How many arms in that spiral galaxy? How elongated is that ellipse? Does the image appear to depict a merger of multiple galaxies?

The dissemination of small tasks to Web users is the foundation of Amazon's commercial Mechanical Turk platform, but Galaxy Zoo 2 is powered by enthusiasm rather than financial incentives. A similar scientific project thrown to the masses is FoldIt, which allows users to manually manipulate the structures of virtual proteins.

The first Galaxy Zoo found user enthusiasm to be plentiful: 150,000 volunteers submitted classifications of a million galactic photographs, assessing each of them dozens of times over. And Galaxy Zoo 2 appears to be a hit, too—according to the project's staff blog, an onslaught of traffic on day one necessitated a move to a more powerful computer, and for a spell on Wednesday afternoon (day two) the Galaxy Zoo Web site was down again.

Photo of overlapping galaxies courtesy of NASA, ESA and the Hubble Heritage Team (STScI/AURA)