'Large Quasar Group' discovered: the largest known structure in the universe

(CBS NEWS) -- Astronomers have spotted the largest structure ever seen in space. The object is so massive that, in the words of one scientist, it will change astronomy's "current understanding of the scale of the universe."

The structure is a large quasar group, a collection of gigantic galactic cores held together by a supermassive black hole. The group, or LQG, stretches 4 billion light-years across.

"While it is difficult to fathom the scale of this LQG, we can say quite definitely it is the largest structure ever seen in the entire universe," Roger Clowes, lead author of the study and a professor at the University of Central Lancashire in the U.K., said in a statement. "This is hugely exciting, not least because it runs counter to our current understanding of the scale of the universe."

Indeed, it is hard to wrap one's head around the sheer scale of the LQC. For comparison, our galaxy - the Milky Way - measures roughly 100,000 light-years wide. The nearest galaxy to our own, the Andromeda galaxy, is 2.5 million light-years away - less than one-thousandth of the width of the LQG.

Dr. Clowers and his team observed the gigantic structure via data gathered by the Sloan Digital Sky Survey. The discovery of the LQG runs counter to the prevailing theory that such massive objects should not exist. It would seem to violate the cosmological principle, the idea that the universe is more or less the same no matter when you are.

But the discovery of the massive LQG may call for a recalibrating of that theory.

"Our team has been looking at similar cases which add further weight to this challenge," Clowes said. "And we will be continuing to investigate these fascinating phenomena."

The study was published in the Monthly Notices of the Royal Astronomical Society.