The Biggest Thing Ever in Space?

S A N  D I E G O, Jan. 9 -- A supercluster of quasars and galaxies massedtogether across 600 million light years of space is the largeststructure in the observable universe, astronomers say.

In a study presented Monday at the national meeting of theAmerican Astronomical Society, researchers reported that thestructure, which includes billions upon billions of stars, isbelieved to be 6.5 billion light years away.

“We have found nothing bigger in the [astronomy] literature andnobody has brought to our attention anything bigger,” said GerardWilliger, a researcher at the National Optical AstronomyObservatories now working at NASA’s Goddard Space Flight Center inGreenbelt, Md.

Just Below Leo

When viewed from Earth, the structure is just below the centerof the constellation Leo the Lion. It stretches across an expanseof the sky of two degrees by five degrees, or an area about fortytimes that of the full moon as seen from Earth.

Williger said it is not known if the gathering of quasars andgalaxies is bound together gravitationally or if it is a chancecluster formed by a ripple in the smooth expansion of the universethat followed the Big Bang, which is thought to have set off theformation of the universe.

“This may be an artifact of the Big Bang,” he said,speculating that conditions at that point in space may have beenuniquely ripe for the quick formation of stars, galaxies andquasars.

That such a large structure could form so quickly after the BigBang calls into question some of the traditional theories of howthe universe evolved, Williger said, since it is difficult toexplain how gravity could pull together such an immense cluster ina relatively short time. Further study, which would includecalculations of the mass in the structure, may yield newunderstanding.

“A successful theory has to explain the extremes,” saidWilliger.

It's Not Just Big — It's Also Very Old

Light from the galaxies began its long journey about 6.5 billionyears ago when the universe was just a third of its present age andthe solar system, including the Earth, had not yet been formed, hesaid.