3-D Galaxy Map Reveals Cosmic Neighborhood

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Our galaxy and its closest neighbors are moving about at 375 miles per second, relative to the cosmic microwave background radiation, the remnant energy from universe's birth.
T.H. Jarrett (IPAC/SSC)

THE GIST

— A 3-D map of our cosmic neighborhood was more than a decade in the making and includes 95 percent of the sky.

— The survey should reveal what is tugging on the Milky Way and its immediate neighbor galaxies.

The most detailed, three-dimensional map of our corner of the universe, a survey more than a decade in the making that covers 95 percent of the galaxies out to a distance of about 380 million light years from Earth, has been unveiled.

"This is pretty much the best sky coverage you're ever going to hope to get for a galaxy survey," astronomer Karen Masters, with the University of Portsmouth in the United Kingdom, said Wednesday at the American Astronomical Society meeting in Boston.

The infrared survey features about 45,000 galaxies, including those residing in the 20 percent of the sky that can't be seen in visual light because they are blocked by gas and stars.

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"In the infrared, we're less affected by the gunk in the Milky Way," Masters said.

The only incomplete section of the map is what's behind the Milky Way's core, an area so jammed with stars "there's no hope of seeing behind it," Masters said.

Astronomers will use the survey for dozens of projects including an attempt to figure out what is pulling on the Milky Way. Our galaxy and its closest neighbors are moving about at 375 miles per second, relative to the cosmic microwave background radiation, the remnant energy from universe's birth.

"What's causing that (motion) is gravity and finding the source of that gravity has been a long-standing issue in astronomy," Masters told Discovery News.

"Only by making an all-sky map can you count all the galaxies that are there and try to determine where that motion comes from. We should now be able to account for the motion," she said.

Of particular interest, is a newly revealed massive structure in the southern sky, scientists pointed out.

Mostly though, the new survey is opening eyes to previously unknown connections between structures.

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"For example, you can see a connection with the northern and southern hemispheres going right across the plane of the Milky Way. That was cut off before. Now we can see that these things actually stretch well across. They're gigantic structures," said astronomer Thomas Jarrett, with the California Institute of Technology.

"It's giving us not just a complete picture, but a new picture," he said.

"It also speaks to our desire to understand our place in the universe," added Masters. " I wouldn't be happy if we didn't have a complete map of the Earth. It's nice to have a complete map of where we live."

The research will be published in an upcoming issue of The Astrophysical Journal Supplement.

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