Play 'Cosmic Slot Machine' and Help Astronomers
These two spiral galaxies are in an early stage of merging. They have strongly disrupted shapes and an astonishing number of blue knots of star formation. The system, Arp 256, is located in the constellation of Cetus, the Whale, about 350 million light-years away.
Credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA)-ESA/Hubble Collaboration and A. Evans (University of Virginia, Charlottesville/NRAO/Stony Brook University)

A new website will let people play a form of "cosmic slot machine," matching up images of colliding galaxies with millions of simulated mash-ups to find the best model.

Astronomers call these cosmic collisions "galactic mergers." Studying these mergers could explain why the universe has the mix of galaxy types ? from those with wound-up spiral arms to compact balls of stars ? that it does.

And it turns out that the human eye is much better than a computer at matching up images of real mergers with randomly-selected images of simulated mergers.

The new website aims to put this human talent to use.

Galaxy Zoo Mergers, which goes live on Nov. 24 at is an international project led by scientists from Oxford University in the U.K. and George Mason University in Virginia.

"Visitors to the Galaxy Zoo Mergers site use what?s rather like a giant slot machine, with a real image of a galactic merger in the center and eight randomly selected simulated merger images filling the other eight 'slots' around it," said Chris Lintott of Oxford University?s Department of Physics and a team member.

"By randomly cycling through the millions of simulated possibilities and selecting only the very best matches they are helping to build up a profile of what kind of factors are necessary to create the galaxies we see in the Universe around us ? and, hopefully, having fun too!" Lintott added.

Users can do more than simply select images, they can also take direct control of the simulations ? choosing 'more' or 'fewer stars' or 'flipping' galaxies ? in order to provide an exact match to what we see in the Universe.

"Whilst we're challenging the 250,000 existing users of the original Galaxy Zoo site to take part in this new project, anyone is welcome to join in ? you don't have to be an expert, in fact our evidence shows that not being an expert actually makes you better at this sort of task," said George Mason astronomer John Wallin.

The project will focus on around 3,000 images of real galactic mergers identified through the Galaxy Zoo project ? it also features some new images of these mergers taken by the Hubble Space Telescope.

The next stage will be to investigate the 'before' and 'after' of these colliding galaxies to work out what caused them and what will happen next ? rather like trying to capture the slow motion detail of the moments before a car crash and predict the aftermath.

"These collisions take millions of years to unfold and so all we get from the Universe is a single snapshot of each one. By producing simulations, we will be able to watch each cosmic car crash unfold in the computer," said Anthony Holincheck, a graduate student at George Mason University and team member.

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