Galaxy zoo! Over 83,000 citizen scientists from around the world have helped create a catalogue, 10 times larger than any previous list, on more than 300,000 nearby galaxies to learn more about our universe.

The project, named Galaxy Zoo 2, is the second phase of a crowd-sourcing effort to categorise galaxies in our universe.

Researchers say computers are good at automatically measuring properties such as size and colour of galaxies, but more challenging characteristics, such as shape and structure, can currently only be determined by the human eye.

An international group of researchers, led by the University of Minnesota, has just produced a catalogue of this new galaxy data.

“This catalogue is the first time we’ve been able to gather this much information about a population of galaxies,” said Kyle Willett, a physics and astronomy postdoctoral researcher in the University of Minnesota’s College of Science and Engineering and the paper’s lead author.

“People all over the world are beginning to examine the data to gain a more detailed understanding of galaxy types,” Willett said.

Between February 2009 and April 2010, more than 83,000 Galaxy Zoo 2 volunteers from around the world looked at images on-line gathered from the Sloan Digital Sky Survey.

They answered questions about the galaxy, including whether it had spirals, the number of spiral arms present, or if it had galactic bars, which are long extended features that represent a concentration of stars.

Each image was classified an average of 40-45 times to ensure accuracy. More than 16 million classifications of more than 300,000 galaxies were gathered representing about 57 million computer clicks.

Researchers estimate that the effort of the volunteers on this project represents about 30 years of full-time work by one researcher.

“With today’s high-powered telescopes, we are gathering so many new images that astronomers just can’t keep up with detailed classifications,” said Lucy Fortson, a professor of physics and astronomy in the University of Minnesota’s College of Science and Engineering and one of the co-authors of the research paper.

“We could never have produced a data catalogue like this without crowd-sourcing help from the public,” said Fortson.

Fortson said Galaxy Zoo 2 is similar to a census of the galaxies. With this new catalogue, researchers now have a snapshot of the different types of galaxies as they are.

The catalogue is available online at data.galaxyzoo.org, and the research was published in the journal Monthly Notices of the Royal Astronomical Society.

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