Galaxy Zoo

StarDate: March 11, 2009

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It's a jungle out there -- a universe filled with billions of galaxies. And like zoologists separating animals into different species, astronomers try to bring order to the galactic zoo by sorting these vast "cities" of stars into their own categories.

For the last couple of years, they've had some help. More than 150,000 people have been participating in a project called Galaxy Zoo. They look at pictures of galaxies and answer a few questions. The answers help astronomers sort the galaxies into different categories.

In the first phase of the project, volunteers sorted about a million pictures. All of the galaxies were photographed by the Sloan Digital Sky Survey telescope in New Mexico.

The goal isn't just to put the galaxies into different stacks, though. Instead, professional astronomers use the information to ponder basic questions about how galaxies form, how they evolve, and how they interact with each other. The project has already revealed, for example, that spiral galaxies don't seem to have a preference for spinning clockwise or counter-clockwise.

The project has also revealed some new mysteries for scientists to ponder, and we'll talk about one of those tomorrow.

Galaxy Zoo is embarking on a second phase that asks more-detailed questions. The answers -- from people just like you -- will help astronomers continue to sort out the galactic zoo. To sign up for the project, visit the Galaxy Zoo web site at

Script by Damond Benningfield, Copyright 2009

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