Scientists need help sorting through an unusual digital photo album: Pictures of aboutone million galaxies.

They are asking volunteers on the internet to help classify the galaxies as either elliptical or spiral and note, where possible, in which direction they rotate. It would be the largest galactic census ever compiled, something scientists say would provide new insight into the structure of the universe.

"We're in the golden era of astronomy," said Bob Nichol, an astronomer at the University of Portsmouth in southern England. "We have more data than we can assimilate, and we need help."

'We have more data than we can assimilate, and we need help.' —Bob Nichol, astronomer

Astronomers say computer programs have been unable to reliably classify the star systems.

Without volunteers, researchers would need years to wade through the photographs, which were taken automatically by a massive digital camera mounted onto a telescope at the Apache Point Observatory near Sunspot, N.M., Nichol said. With 10,000 to 20,000 people working to classify the galaxies, the process could take as little as a month.

Volunteers would sign on to the website, galaxyzoo.org,complete a brief tutorial and pick through one galaxy after another. The galaxies would be identified by several people to guard against errors and pranks, and scientists would rule on any disputes.

The catalogue would help researchers understand how galaxies form and interact.

"At some level, what we learn about these galaxies could tell us something quite fundamental about cosmology and particle physics," Nichol said.

The project was inspired by similar projects at NASA, such as Stardust(at)home, which enlisted the help of thousands of volunteers to sift through grains of space dust gathered during a 2006 mission.