Mysterious web of "dark matter" found

OTTAWA - Canadian and French scientists have found enormous chunks of super-mysterious dark matter each 270 million light-years wide, stretching across the sky like giant cobwebs.

And it's all invisible. Dark matter is material that we can't see or detect with any known instrument. But it's suspected of being six times more common in the universe than regular matter - stars and planets and your body.

This huge network of dark matter shows up only indirectly. Its gravity is strong enough to distort the light of entire galaxies - hundreds of millions of stars at a time.

Astronomers call this a "lensing" effect: They see the light of ordinary stars bending, as if through a lens, which tells them there's some invisible object to cause that bending. Voila - dark matter.

The size of this dark mass is mind-boggling. At 270 million light-years wide (i.e. a distance that would take a beam of light 270 million years to cross) it's 2,700 times wider than our own Milky Way galaxy. And the Milky Way is no shrimp: It holds at least 200 billion stars.

The discovery comes from the Canada-France-Hawaii Telescope, which sits high on an extinct volcano called Mauna Kea to rise above the lower atmosphere. "We have a significant detection of many structures of that size, not (just) a single one," said Ludovic Van Waerbeke of the University of British Columbia, the lead Canadian in the group.

"It's like a web. If we could see the dark matter with the eye, it we would see a web of dark matter structures across the sky," each in the 270-million- light-year scale.

"Galaxies live inside of (these) structures. So those structures are much bigger than any galaxy cluster or even super-cluster that you would find in the sky."

Dark matter is a little like a cobweb, and our visible galaxy is like like a fly in it, he said.

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