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Wall of gas divides
cosmic metropolis

...A new study from the Chandra X-ray Observatory unveils the star-forming factory NGC 604 as a divided neighbourhood...

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Supermassive black holes not guilty of shutting down star formation

...Galaxies cease star formation long before their supermassive black holes have the power to do the job themselves...

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C1XS takes first taste of lunar X-rays

...The UK-built C1XS instrument flying aboard the Chandrayaan-1 orbiter has successfully detected its first X-ray signature from the Moon...

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Video archive

STS-120 day 2 highlights

Flight Day 2 of Discovery's mission focused on heat shield inspections. This movie shows the day's highlights.


STS-120 day 1 highlights

The highlights from shuttle Discovery's launch day are packaged into this movie.


STS-118: Highlights

The STS-118 crew, including Barbara Morgan, narrates its mission highlights film and answers questions in this post-flight presentation.

 Full presentation
 Mission film

STS-120: Rollout to pad

Space shuttle Discovery rolls out of the Vehicle Assembly Building and travels to launch pad 39A for its STS-120 mission.


Dawn leaves Earth

NASA's Dawn space probe launches aboard a Delta 2-Heavy rocket from Cape Canaveral to explore two worlds in the asteroid belt.

 Full coverage

Dawn: Launch preview

These briefings preview the launch and science objectives of NASA's Dawn asteroid orbiter.

 Launch | Science

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The Hitchhiker's Guide to

the Galaxies


Posted: 17 February, 2009

The doors to Galaxy Zoo 2 are officially opened today, calling on the public to delve deeper into 250,000 galaxies in the search for the weird and wonderful.

The first Galaxy Zoo asked members of the public to say whether a galaxy was spiral or elliptical, and which way it was rotating, but Galaxy Zoo 2 will ask for details on the number of spiral arms, the type of central bulge and if a merging event is taking place. "The first Galaxy Zoo provided us with a Rough Guide to the sky and now we want our users to fill in all the details and create a real Hitchhiker's Guide to the Galaxies," says Dr Chris Lintott of Oxford University, one of the founders of Galaxy Zoo.

Hanny's Voorwerp - the strange green ghost like gas cloud - was just one of the exciting discoveries of Galaxy Zoo volunteers. Image: ASTRON/Dan Herbert/Isaac Newton Telescope.

Astronomers came up with the idea of getting online volunteers
involved because the human brain is still better at doing pattern
recognition tasks than a computer. The initiative was met with resounding enthusiasm and in the last 18 months 80 million classifications of galaxies were submitted on one million objects by more than 150,000 armchair astronomers from all over the world.

"The response from the public was absolutely overwhelming and, with their help, we've been able to learn a lot about how galaxies evolve and how they relate to their environment," says Dr Kevin Schawinski of Yale University, another of Galaxy Zoo's founders. "With the detail from Zoo 2, we'll be able to discover even more about how galaxies work."

Unusual discoveries have already been made by the Zoo’s visitors, including over 3,000 rare cosmic collisions, and the well-known Hanny’s Voorwerp, a huge green irregular gas cloud, discovered by Dutch Galaxy Zoo volunteer Hanny van Arkel. Follow up observations revealed a jet of highly energetic particles generated by a massive black hole lurking at the centre of a neighbouring galaxy, that had cleared a path through to Hanny's Voorwerp, illuminating a small part of a large gas cloud that partially surrounds the galaxy.

"Galaxy Zoo has given everyone with a computer an opportunity to contribute to real scientific research. We want people to feel truly involved in the project and keep them up to date with what we're doing and with the results they're generating," says Dr Steven Bamford of the University of Nottingham.

Visitors to Galaxy Zoo can spend any length of time working on the site - even one classification will add value and insight into understanding how galaxies, including our own Milky Way, formed and evolved. Galaxy Zoo 2 will also add an element of competition as galaxies will be pitted against each other in "Galaxy Wars" and users can compete against their friends to describe more objects as well as record their best finds.

"In this International Year of Astronomy, it's great to have so many people looking at these beautiful image of galaxies from the Sloan Digital Sky Survey," says Professor Bob Nichol of the University of Portsmouth, a member of the original Galaxy Zoo team. "No single professional astronomer has ever looked at all these images and sometimes astronomers miss the wonder of what they are. I think the public get this better than us."

To visit the Galaxy Zoo go to