Identifying galaxies: everyman's task

Astronomers are recruiting ordinary people around the world to help classify 1 million galaxies.

from the July 16, 2007 edition

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And while the team initially thought participants would post a new result once every one or two seconds,"We've gotten 20 times that," says Alex Szalay, a professor of physics and astronomy at The Johns Hopkins University and an architect of the Sloan Digital Sky Survey's database.

They drew their inspiration for Galaxy Zoo from NASA's Stardust mission, which captured and returned samples of interstellar dust to an eager horde of scientists back on Earth. It also captured other bits of cosmic flotsam and jetsam in a special dust-gathering gel. Stardust scientists asked home-computer users to look at online images of the gel to help identify the tracks that signaled dust.

"Looking at galaxies is much more interesting than looking at dust!" Lintott quips.

A clue for a 'universal' riddle

Researchers are looking at immediate uses for the data people provide. For Lintott, elliptical galaxies and how stars form in them are of keen interest. Theories of galaxy formation suggest that elliptical galaxies should form late in the universe's history; "they should just be forming now," he says. But some of the oldest stars in the universe are found in these galaxies. One approach is to look at elliptical galaxies nearby that are forming stars to see if they hold clues to this paradox. This effort to classify galaxies will help him select ones for study, Lintott adds.

The project was formally announced last Wednesday. Within the first 60 hours, 40,000 people signed up. Web hits vaulted to 6.5 million. The project's initial array of Internet servers ground to a halt under the load. So far, some 650,000 galaxies have received an initial classification. And while 40,000-plus pairs of eyes seem like plenty to do the job, more are needed. "We need to get 10 to 20 classifications per galaxy," Dr. Szalay says. This would allow the scientists to more readily determine a galaxy's most likely shape. "We still have a lot of galaxies no one has looked at."

The project, which also includes researchers from the University of Portsmouth in England, is drawing positive reviews from participants. Writes one member of a British government agency in an e-mail to the project team: "Just had a go at my first few galaxies. A great idea, and genuinely humbling to think that you're looking at something rarely or never seen before."

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