for National Geographic News
Japanese astronomers have discovered what they call the largest object in the universe: a colossal structure 200 million light-years wide that resembles a swarm of giant green jellyfish.
Using the Subaru and Keck telescopes on the Mauna Kea volcano in Hawaii, the research team found an enormous object containing clusters of galaxies surrounded by gas clouds known as Lyman alpha blobs.
Because the object is so far away, the astronomers are actually looking at something from 12 billion years ago, a mere 2 billion years after the universe is believed to have been formed in the big bang.
This young galactic blob could reveal how and when the earliest galaxies formed. (See a photo of the oldest known galaxy cluster [February 17, 2005].)
Ryosuke Yamauchi from Tohoku University in Sendai, Japan, and his colleagues used the Subaru Telescope to study a region of the universe known to contain large concentrations of gas.
By placing a special filter on the telescope, they were able to concentrate on the narrow range of light wavelengths expected from galaxies at extreme distances.
With these special "goggles" Yamauchi and his team were able to pick out the giant blob. It spreads out along three wavy tentacles.
Each arm is packed with galaxies around four times closer to each other than the universe's average.
Previously known structures with such high density are much smaller, only about 50 million light-years across.
"The densest regions in the universe are the places where galaxies are thought to have formed first. Because this is one of the biggest structures known, it must be one of the very first to have formed," said Philip Best, an astronomer at the Institute for Astronomy at the University of Edinburgh in the U.K.
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