IE 11 is not supported. For an optimal experience visit our site on another browser.

See the big picture

Even as two astrophysicists are being honored with a Nobel Prize today for seeing the big picture in the universe's background radiation, another astronomical team has released a different set of cosmic pictures - mapping out the huge concentrations of mass in our own celestial neighborhood. The astronomers behind the 2MASS Redshift Survey say their pictures represent the "largest full-sky, three-dimensional survey of galaxies ever conducted."

The survey's density maps could also help scientists figure out the distribution of invisible dark matter and mysterious dark energy in the cosmos - two factors that together account for 96 percent of the universe's content.

2MRS
A slice from the 2MASS Redshift Survey shows the

Great Attractor, a galaxy supercluster toward which

our own Milky Way is hurtling. Click on the picture to

watch a video narrated by MSNBC's Alan Boyle.

The maps go out to a distance of 600 million light-years - which is unimaginably far in human terms but comfortably close in astronomical terms. Even though the volume covered represents only a small fraction of the observable universe, it's a sampling that should let scientists test their theories about where the dark matter lurks.

"This extraordinarily detailed map of the Milky Way's cosmic neighborhood provides a benchmark against which theories for the formation of structure in the universe can be tested," Matthew Colless, director of the Anglo-Australian Observatory and leader of the 6dF Galaxy Survey, said in today's news release.

The map was developed by painstakingly measuring the redshift values for 25,000 galaxies over most of the sky, detected by the Two Micron All Sky Survey, or 2MASS. Some redshifts were obtained from the 6dF survey, a deeper look at the southern sky.

Redshift measurements can tell astronomers roughly how far an object is - and the three-dimensional map was developed by grouping together galaxies with similar redshifts.

As a result, scientists charted the location of massive galaxy superclusters - including our own Virgo Supercluster as well as the Great Attractor, which is tugging gravitationally at the Milky Way and its neighbors in the Virgo Supercluster. Scientists say we're hurtling toward the Great Attractor, roughly 150 million to 250 million light-years away, at a speed of a million mph.

There's an even bigger supercluster farther out: the Shapley supercluster, at a distance of 400 million light-years. The 2MASS Redshift Survey confirmed that the Shapley concentration and the Great Attractor are indeed separate superclusters.

Scientists used the signatures of all these galaxies to map dark matter as well as visible matter. "Fortunately, on large scales, dark matter is distributed almost the same way as luminous matter, so we can use one to help unravel the other," said Pirin Erdogdu of Nottingham University, the lead author of a paper accepted for publication by the Monthly Notices of the Royal Astronomical Society (PDF file of preprint).

In the future, the predicted motions of galaxies on the map will be compared with more direct measurements of the galaxies' velocities, providing "a new and stringent test of cosmological models," Colless said.

Check out this video for the full map. And for other types of really, really big pictures, check out the Wilkinson Microwave Anisotropy Probe's view of the big bang's aftermath (as well as Cosmology 101 from the WMAP team),  the Sloan Digital Sky Survey's 3-D universe map and this "complete map of the universe." Now how cosmic is that?